How To Refill Nitrogen-Filled Tires

Q: I just purchased a car with nitrogen-filled tires. I know they aren't supposed to leak like air-filled tires can but leaks DO happen. So what do you do if a slight pressure drop happens? How much air can be put in without losing the nitrogen benefit? I would hate to have to go to a tire dealer and wait for a tech to put some in. Do you know of a company that markets aerosol cans of nitrogen similiar to "Fix A Flat"?

A: Most places that fill tires with N2 will top them off for free. I like the aerosol can idea, though. No one is doing that that I’m aware of.

Why Does Water Collect Inside My Car's Headlights?

Q: My headlights are always collecting water inside. The dealer says he can replace them, but they’re very expensive, and he wouldn’t guarantee that the new headlights wouldn’t collect water also. I took out the headlamp assemblies and coated all of the seams between the clear lens and the back with bathtub caulk, and gooped up the rubber dingus that goes over the headlight wires with a lot more caulk, but it didn’t help a bit.

A: Let’s examine why there is water inside the lamp assemblies in the first place. As the outside temperature goes down and your nice warm headlamps cool off (either from being in the sun or just from being turned on), cooler, moister outside air trickles into the housings. The housings are vented top and bottom to allow for pressure differences, or they would quickly crack and fail. When the clear plastic lens is even a little bit cooler than the air inside the housing, droplets of moisture will condense on the inside of the lens. That’s normal. When the outside temperatures come back up in the morning, the moisture will evaporate.

Some vehicles don’t vent as well as others. Some drivers keep their cars parked in shady, damp areas or in cool, damp underground parking structures. And the moisture collects not as tiny droplets of mist but as what looks more like raindrops, and can even run down the glass and pool inside the housing.

Check to see if there’s a Technical Service Bulletin for your make and model of vehicle. If so, there may be a retrofit housing or an upgrade to the venting system. If not, you’re on your own. The first thing to try, if all you have is droplets, is to leave your headlights on while driving for a couple of hours, forcing the moisture off. If you have a spoonful or more splashing around, you may need to remove the housing and dry it out. Pour off the excess water, then add a few ounces of rubbing alcohol to the housing, sloshing it around and pouring it out. Repeat. Let the housing dry for a couple of hours in the sun or inside a nice warm house, preferably in some air that’s moving. Check that any vents aren’t plugged with spider eggs or mud. Install the housing and try to park facing south.

How Your Headlights Work

Headlights have come long way since the crude lamps that lit the way for the first cars. Modern headlights use deceptively interesting tech to produce your car's beams, and the next generation—based on lightweight, energy-efficient LEDs—are on the way.

I'm willing to bet that drivers only think about headlights during one of two events: when for some reason they can't see at night, or when an oncoming car blinds them. Like the alternator, these critical pieces are overlooked—until they don't work. And that's a shame, because for the gearhead, there's a lot of interesting tech behind the glass. Like, for example, did you know that an HID headlight is like a lightning bolt in that a glowing arc of electricity illuminates the fixture? Plus, automakers are calling on headlights to increase not only safety but also fuel efficiency.

Knowing how your lights work will better prepare you to keep them maintained, so you're more likely to see that deer before it runs into your path. Besides, the rapid evolution of headlight tech is interesting in itself. Here's a primer.

The Old-Fashioned Way

The first cars used crude lamps fueled by either kerosene or (gasp) acetylene. About 100 years ago, the open flames were replaced with a small electric bulb housed between a polished reflector and a lens. These lights weren't sealed well, so the reflector corroded quickly, making the already insufficient lights even dimmer—and worse, they provided plenty of glare to oncoming traffic. These types of lights were made illegal in 1941, a scant year after the introduction of the sealed beam.

Sealed Beams

A sealed-beam headlamp is nothing different from a giant household bulb, a tungsten filament housed in a glass enclosure that's sealed and filled with inert gases. The reflector is inside the glass envelope. Like household bulbs, these gradually lose brightness as the tungsten evaporates from the filament and deposits on the reflector. Dippable high-and-low beams didn't come along until the '20s. Brightness and beam control in this era were inconsistent because of poor manufacturing tolerances. And the inside of the poorly sealed glass lens easily corroded, further reducing the brightness. Sealed-beam lights were cheap partly because they came in only three sizes—5- and 7-inch round and one square size—but more important, the standardized sizes limited styling differences among cars. Automakers started replacing sealed-beam lights with quartz-iodine technology in 1973.

Quartz-Iodine

Sylvania Silverstar H13 1. Quartz Glass 2. Support Strut 3. High Beam 4. Low Beam

QI is the predominant automotive lighting technology today. Legal in the U.S. since 1984, it uses a small bulb that resides inside a reflector/lens assembly. Thanks to modern sealing materials and techniques, the reflector is far less likely to corrode from moisture intrusion. The high-temperature quartz glass envelope allows the filament to remain at a much higher temperature, for a light that's closer to natural daylight. The higher temperature means a lot more light for the power consumed, but also makes the tungsten filament evaporate and redeposit on the glass, gradually reducing light output. To combat this, halogen bulbs are filled with iodine or bromine rather than the customary inert gas. The halogen combines with the tungsten vapor coating the cooler glass, then disassociates when it touches the hot filament, basically redepositing the evaporated tungsten back where it started.

Manufacturing these cylindrical bulbs is very high-tech. After the filaments are sealed to the glass at the bottom, most of the air is evacuated from the top. While a propane flame heats the neck in the top of the bulb to a semiliquid state, a jet of liquid nitrogen cools the base to minus 321 degrees F. Then a pellet of frozen gases is dropped in. Instantly, the hot, soft glass at the top is crimped, sealing the envelope. When the temperatures equalize and the gaseous pellet boils, the pressure inside rises to 4 to 5 atmospheres. The H13 high–low beam lamp shown in the lead photo is the industry's latest version. Computer vision systems carefully tweak the position of the filaments in each bulb as it's assembled, maintaining tolerances within 0.004 inch—which means replacing a lamp shouldn't require reaiming the headlamp. The high-beam filament sits at the precise focal point of the reflector, providing the best illumination up the road. The low-beam fila­ment sits slightly off the focal point to spread the beam and establish a cutoff pattern to keep glare out of oncoming drivers' eyes. Some quartz-lamp systems rely on the use of a metal shield to provide the cutoff pattern.

The color of bulbs is expressed as a function of the temperature of the light emitted. A QI bulb is around 3400 degrees K, as compared to natural sunlight, which is considered to be around 6000 K. Recently, we've started to see QI lights that have a blue-white color, not the usual warm yellow light. These are aftermarket bulbs with different filaments and glass coatings that attempt to emulate the blue hue of expensive high-intensity-discharge (HID) lights (I'll get to HID lights in a minute). While these bulbs do raise the color temperature, they don't get close to an HID's 5000-plus K color. Oh, and they don't necessarily raise the light output either. So what's the point? Style­—it's one way to spend $20 and acquire the cachet of $2000 HID lamps.

How to Break in a New Car

It’s a thing of beauty: A brand-new car, shiny and crisp. It makes you want to spend the whole evening walking around it. Pretty soon, the neighbors wander over to congratulate you—and to render advice.

Break it in carefully, one says: “No more than 30 miles per hour until it has 1000 miles on the odo.”

“No,” another says. “Drive it like you stole it, if you want it to be fast.”

Others recommend synthetic oil, or nitrogen in the tires, or a mouse-milk oil additive, guaranteed to double fuel economy.

The ritual of breaking in a new car is part of the body of knowledge we refer to as conventional wisdom. It’s not necessarily wise, and the technology of building a modern automobile has evolved to the point where a lot of “wisdom” is obsolete. Few cars specify a break-in procedure anymore, simply cautioning you to avoid extreme acceleration or extended idling for the first thousand miles or so, and there’s little in the way of extra service up front. Some don’t even mandate an oil change until 6000 miles. We think your new ride deserves better. Here are a few tips.

Engine Cylinder Walls

Piston rings don’t rely on their spring tension to seal against the cylinder bores. Instead, combustion gases work their way between the rings and the piston and force the rings outward. During the first few minutes of engine operation, it’s important that the throttle be opened pretty far at lower rpms to provide this high pressure. Otherwise, the rings won’t burnish the cylinder walls properly, and the engine will have high volumes of blow-by—which means excessive oil consumption and shortened engine life. If you’ve ever seen the car jockeys who drive new cars off the end of the production line into the storage lot, or the transporter drivers zipping up and down the car-hauler ramps, you’ll realize that this all-important step has been performed for you many times. If you’re installing a new engine, simply give it a few seconds of wide-open throttle in a high gear. For the first thousand miles, avoid constant speeds and throttle settings. If you commute in normal stop-and-go traffic, you’ll be fine. I advise against cruise-controlled sojourns across Nebraska.

Bearings

The admonition to keep engine revs low for an extended break-in period stems from the days when bearing and crankshaft manufacturing tolerances were far less rigorous and lubricating oil wasn’t nearly as good. While modern engines are assembled to much the same design clearances, the tolerances are much tighter, meaning the variability is smaller, greatly reducing the possibility of a tight spot. Redlining a fresh motor is generally a bad idea, but there’s no reason you shouldn’t drive normally. I would, however, avoid top-speed testing, drag racing or towing heavy trailers for the first 1000 miles.

Oil

I customarily change the oil in a new engine after about 20 miles, and again at 1000 or so. That 20-mile oil, you would think, would look pretty much like fresh oil right out of the bottle. Wrong. It usually looks more like metal-flake paint, iridescent with tiny particles of metal worn off rubbing surfaces inside the new engines. After a few hours of operation, this completely normal phenomenon slows down as the rings, camshaft, lifters and bearings burnish their respective mating surfaces.

Transmission

The engine break-in procedure also covers the gearbox and the clutch on manual-transmission cars. Most cars with automatic transmissions today are factory-filled with ATF and, supposedly, will never need changing. Some manufacturers are so confident of this that they don’t even have a dipstick or a fill hole. If the specified fluid is a more ­normal mineral oil, I’d change it and clean the pan after a thousand miles or so. The organic linings on the clutch packs shed a lot of debris, and it generally just turns into sludge that lies in the pan. You don’t want wear metals and sludge to get picked up by the pump and start circulating in the expensive bits.

(Photograph by Frederik Broden)

Brakes

New brake pads on new brake rotors don’t really require a break-in procedure. The texture deliberately left on the surface of the iron discs will grind down the fresh surface of the pad material within a few miles. Even so, refrain from high-speed stops or dragging the brakes for a few hundred miles. Racing pads, however, need to be heated up enough to fade and then carefully cooled off, which removes the top layer and provides better fade resistance.

Interior

Avoid the impulse to slather the interior trim with shiny protectants, which can leach the plasticizers out of new vinyl and increase the likelihood of age-related cracks. On the other hand, a generous dousing of Scotchgard on the cloth upholstery and carpets will keep dirt, pollen and mildew from clinging.

Paint

In years past, it was considered a good idea to not wax a fresh paint job for 90 days, to allow the paint to fully cure and any solvents to escape without being trapped under the wax. Modern catalyzed clear-coat paint is as hard as it will ever be as soon as it cures, before the car ever leaves the plant. Applying 3M Paint Protection Film to the leading edge of the painted bodywork will go a long way toward minimizing stone-chip damage. Otherwise, a good coat of wax will repel water, atmospheric pollutants and dead bugs.

NOW YOU KNOW: Is synthetic oil too slippery for proper break-in?

Conventional wisdom says that a new engine should be broken in on conventional mineral oil, regardless of your intentions to use a synthetic for the long haul. The conventionally wise say that synthetic oil is too slippery and won’t let the microscopic high points properly lap themselves in, delaying the break-in process. I say rubbish. Many modern cars, notably such high-performance marques as Porsche, Ferrari and Corvette, are factory-​filled with synthetics. You can bet that somebody has determined that the break-in process will proceed normally with synthetic in the sump of these ultra-high-performance engines. And that goes for your Toyota or Jeep as well.

Nonetheless, I do prefer to use a mineral oil for break-in. It’s $3 a quart versus $7, so I don’t mind changing it after 20 miles and again at 1000.

I would not, however, change the factory-fill synthetic back to mineral for break-in. Those vehicles typically have carefully assembled engines with instructions to do the first oil change at the regular interval, which could be up to 10,000 miles. In those cases, I simply change the oil early, before 1000 miles, just to be safe.

Synthetic oil is a superior product, particularly if your engine operates at the extreme ends of the temperature scale: high-temperature climates, towing or racing. But like any oil, synthetic will become contaminated with atmospheric dirt, wear particles, carbon, partially burned fuel, water and acid. Eventually, even if the oil itself is performing properly, all this extra junk will manifest itself as engine wear.

Also, the first oil change invariably reveals small particles of gasket sealer, chunks of unidentified plastic, the occasional metal flakes that weren’t cleaned off before assembly and even the odd washer or nut. It’s pretty scary. Better this junk come out sooner rather than later.

Convert Your Car to Natural Gas

Between the tank and the engine is the fuel regulator, which reduces the fuel-tank pressure of 3600 psi to a usable 125 psi delivered to the engine. The fuel regulator is heated to prevent freezing from the expansion of the gas. The lower-pressure gas travels to the engine, Chrysler's flex-fuel-capable Pentastar V-6. A flex-fuel engine is important, since it has hardened valves and valve seats, which are necessary for CNG operation. The natural gas is routed through a parallel fuel rail, and a second set of injectors is plugged into a clever adapter designed to accommodate both the gasoline and CNG injectors on the same injection port. Natural gas runs at an ideal air--fuel ratio of about 16.8:1, whereas gasoline runs happily at 14.6:1 for the Pentastar engine. As a result, the programming for the new injectors has to be slightly different. NatGasCar's wiring harness intercepts the signals from the engine-control module and, depending upon which fuel is selected, turns on either the gasoline or the CNG injectors. The signals bound for the gasoline injectors are modified to deliver the appropriate amount of fuel to the natural gas injectors. This way, very little fine tuning is necessary, and the car's engine-control unit does most of the work.

As it turns out, there are very few technological barriers to overcome. In fact, converting existing vehicles to burn natural gas isn't particularly challenging. Unfortunately, if you tried to do it yourself, you'd more than likely run afoul of the Clean Air Act's rules against modifying fuel systems--a violation that could cost you up to $5000 in fines for every day you drive the converted vehicle. So if you want to green your wheels today, the only way to do it is by hiring a certified compressed-natural-gas (CNG) installer to do the job. To get the skinny on aftermarket CNG systems, I visited NatGasCar in Cleveland. It's a startup shop that augments gasoline cars by installing a parallel natural gas fuel system. They showed me their latest creation, a dual-fuel Dodge Caravan intended for airport taxi service. It starts on gasoline and switches over to natural gas once the engine warms up.

NatGasCar's biggest component is also its most crucial and expensive--the compressed-natural-gas fuel tank situated behind the rear seats in the cargo area. The company uses a Type 4 tank, the most advanced kind. It reduces weight with a plastic composite core wrapped in carbon fiber and is rated for severe impact and puncture resistance.

Natural gas has been used in our homes for generations. Americans use it to run water heaters, home furnaces, stoves, clothes dryers, and other appliances. As a fuel it accounts for 24 percent of our total energy consumption nationwide, all but 1 percent in residential applications. And as we reported last fall ("Drilling Down," September 2011), new fracking techniques are tapping domestic reserves that previously were not economically viable. Vast global supplies are projected to last well into the next century even if natural gas replaces gasoline completely. So it should be no surprise that natural gas will remain incredibly cheap. It runs at one-half to one-third the current cost of gasoline on an energy-equivalent measure. In a properly tuned engine, natural gas combustion delivers 20 percent lower carbon emissions and about a 25 percent reduction in greenhouse gases compared with the cleanest gasoline engines, all without damaging existing catalytic converter systems. So right about now you're probably wondering: Why aren't we putting this stuff in our cars?

Fueling Woes

So a new fuel tank and a little bit of tinkering with the fuel injectors and I'm ready to go, right? Unfortunately not. Natural gas is delivered across the country to millions of homes. But what would seem to be the ideal distribution network is actually the biggest headache of natural gas vehicles. Home natural gas is delivered at about 0.5 psi, but natural gas in vehicles needs to be pressurized to 3600 psi. So if you want to use CNG in your car, you'll need a compressor. A National Fire Protection Association safety standard bans compressed gas storage in homes, so a stand-alone multistage compressor pump in the garage must be hooked up to the vehicle's fuel tank, filling it directly. This leads to fueling times of up to 22 hours (even longer than equivalent home charging times for electric vehicles). Honda's Civic Natural Gas is paired with a home compressor system called Phill ($4500), the only commercially available product of its kind. NatGasCar is developing a compressor system capable of 8-hour fill-ups; the current target price is $3500. Some states have incentivized the installation of high-speed filling systems at gas stations, where fill times are as brief as 4 to 5 minutes, much like gasoline's. But these systems cost $750,000 per station to install, and low demand means there are only 941 high-pressure CNG filling stations scattered across the country, mostly in New York, California, Utah, and Texas.

Economics

Okay, okay, it's a pain to fuel CNG vehicles, but is it worth it? Nationwide, natural gas ranges from 79 cents to $1.50 for a gasoline gallon equivalent (gge) of fuel. That's considerable savings over petroleum-based products, especially considering that CNG vehicles get the same or better relative fuel economy per Btu because of the higher octane rating of natural gas. Our test drives indicated no hit to performance, and a perfectly acceptable range of about 250 miles. But there are some pretty extraordinary initial setup costs. A properly installed conversion will run anywhere from $6500 for a basic system to $12,000 for a top-of-the-line installation with a high-capacity, composite fuel tank. If you want a home fueling compressor, tack on another $3500 minimum. Even at the low end, you're looking at spending enough on the conversion to buy more than 1800 gallons of gasoline at today's prices.

Those prices will ultimately determine the fate of CNG vehicles. High gasoline prices historically have caused furious investment in cheaper, cleaner fuels, followed by a collapse in demand when gas prices fall. For now, CNG has a high price of entry that makes it viable only for taxi services and other fleet operators, but over time, economies of scale may bring down the costs for the ordinary car buyer. And if gasoline stays above $3 a gallon, that change may come sooner rather than later.

Car Dealership Service Manager Secret for Auto Repair

Q
What's the worst day of the week to get your car serviced?

A
Friday afternoon after lunch, because the service department is trying to push out as many vehicles as possible. Maybe a car has been there since Monday waiting on parts. Maybe there are a few cars like that. Then people pour in around lunchtime wanting oil changes. And there are the cars there already with appointments, and everyone's in a rush to get it all done. Make an appointment for a Monday morning as early as possible. It's a lot more orderly, and they'll do a better job.

Q
So it's not necessarily more expensive, and they know more about your car. Any other reason?

A
Often times at Jiffy Lube or wherever they're paid by the hour, and they're not necessarily trained to know your vehicle. And that can cost you your engine. If I could get half of what I've charged customers to replace engines that were screwed up by Jiffy Lube and Walmart, for such things as not enough oil, too much oil, the wrong weight of oil, wrong filter, loose filter or any combination of the above, I could have retired a long time ago. There's no point to spending $30,000 to $40,000 on a new vehicle and then trying to go cheap on the maintenance.

Q
What's an example of a common tactic by dealers to pad the bill?

A
So-called shop supplies. That is, and always has been, the biggest crock of crap I've ever seen, and it's been going on for years! It is essentially similar to going to a nice restaurant, getting your check and finding you've been billed for napkins and silverware, which are necessary costs of the food service business. Shop supplies include, but are not limited to, shop rags, lubricants—this isn't the motor oil, transmission fluid, brake fluid and steering fluid they might put in your car—and the cost of disposing of used oil. These are just some of the necessary costs of doing the auto repair business. Some dealers do not charge for them, but most do, and what is considered shop supplies is at the discretion of each individual dealer. I've seen a customer get billed for $30 in shop supplies—on top of their estimate—for the use of three shop rags! For that price, I can buy 20 rolls of shop towels at Auto Zone.

Q
If you got a bill that had shop supplies on it, what would you do?

A
Ask to see exactly what that means. Ask to see the precise items they actually used. Challenge them on it. You might not get them to knock it off your bill, but you should try.



Q
You also said that dealer service departments too often recommend fluid flushes and replacements that aren't called for by the owner's manual. The dealers cite the "severe use" schedule that doesn't apply to the vast majority of us. Should drivers simply veto a service or fluid replacement that isn't recommended—in the owner's manual—under the normal or light-duty service requirements?

A
Yes, you should go by what the owner's manual recommends for normal use. And, yes, this is a common practice, and I hate to admit that. When I was a customer relations manager, I had a service manager who would [bate people into buying the fluid changes] by showing new fluid versus used fluid. She made more than I did just in flush commissions, but had the worst customer satisfaction surveys. I have always stuck to the manufacturer recommendations, and my Escape has over 310,000 miles on it. Less than five percent of drivers operate their cars under conditions that would be deemed "severe." The ones who do are usually taxi or pizza-delivery drivers, or those who frequently take their SUV or truck off-road.

Q
What's the single best piece of advice you'd offer to a friend about servicing his car at the dealer?

A
A dealer won't come right out and say it, but if you have your regular service work done at the dealer... (because warranty work pays the dealer a lot less than service work), your value to the dealership increases. Here's an example: Suppose your vehicle goes out of warranty and a week later you have a catastrophic failure. If you have shown loyalty to the dealership by using them for regular service work, they will be more inclined to help you—as opposed to the person who buys a car there and takes it somewhere else for regular service, and only brings it in for warranty work.

Q
So it's about building a relationship with the dealer?

A
Yes. You need to know that dealers make very little on car sales. And warranty service doesn't pay as much as regular maintenance. But if they see that record that you've been loyal to them, they'll likely be loyal to you.



Q
What's a sign that a dealership doesn't value that relationship?

A
Constant turnover at the service desk. You should get the name of the person at the desk. You should ask for him or her. If that person's different every time, it's not a good sign. Good auto service work starts with a relationship between the advisor and the customer, and that cannot be obtained when the customer sees a new advisor every time he comes in. I always knew the person's car, I pulled up its history, and that's something people appreciate. But if that person is new or is always changing, they don't know you or your car — stuff gets missed, and that's typically not good for you or your car.

Q
How come a dealer might charge you 30 percent more for a part than you can find it for at AutoZone?

A
It's one of the hang-ups I've always had about domestic automakers. You can often buy their parts cheaper at the auto parts store than you can at the dealership parts counter. And the dealer knows this, but he can't do anything about it. The problem is that even though that's true, the dealer doesn't want to install a part that he didn't source, because if it fails, how does he warranty it?

Q
So what do you do as the customer?

A
There's not a lot you can do. They can install the part if you went out and bought it, but most won't.



Q
Speaking of AutoZone, you can take your car there to have them read what a Check Engine light means. How accurate will that reading be?

A
Check Engine lights are big moneymakers for dealers and also the bane of a service manager's existence. Anyone can use a code reader. But what does the code mean? For every code there need to be additional diagnostics. I've had customers come in and tell me to swap some part, because they're sure it's the problem. But all that is is a really expensive guess. They might be right 10 to 20 percent of the time, close 20 percent of the time, and dead wrong 60 percent of the time. I had a customer go through six oxygen sensors when all it was was a shorted wire.

Q
What's the smartest thing you can buy from the dealer?

A
A brand-name extended service contract. So if you're buying a Ford, get a Ford contract. If it's a Toyota, buy the Toyota contract. The opposite is also true. Never buy the extended service contract that's generically offered through the dealer but isn't backed by the brand of car they sell.

Q
How come?

A
Because the people who fulfill the generic contracts are paid by how little service they have to do. So they fight the dealer on every penny. They'll want to see the entire labor record on the car. They won't want to pay for parts. They'll fight on the cost of the labor. In the end, the customer is going to have to eat some of that cost, even though the contract supposedly covers the car.

Q
What's a good reason to take your car to the dealer for routine maintenance, rather than to the guy with two bays and a private shop?

A
Let's use Ford as an example. If you own a Ford vehicle, the Ford dealership will have Ford-trained technicians who work on Ford vehicles 95 to 100 percent of the time. During that time they will use Ford resources and Ford training to repair your vehicle correctly, and (ideally) they take Ford classes and attend Ford schools to keep up on their knowledge. With the other guy, it's a tossup—he may work on two Fords one week and not see another for a month. Also, on regular maintenance it can sometimes be cheaper, not more expensive. To get an oil change and tire rotation where I live, the Ford dealer is $38.95 plus tax, and Sears wants $75.

Why Your Auto Spying on you?

What can you do about it? If you're a new-car buyer, not much. But pay close attention to the language of the user agreement for any telematics service—if you don't like what you read, opt out of the service. With EDRs, it's enough simply to know your rights. The law is still playing catch-up to the technology, but at this point you do not have to surrender the EDR data to the police without probable cause, a warrant, or a subpoena.

Most navigation systems are separate from a car's computers and cannot track your location. Nav systems rely on the Global Positioning System, which is a one-way data stream to the car. Your car may know where it is, but nobody can track it via the GPS link, and no location data is stored in the EDR.

But everything changes when you add a cellular connection. Cars equipped with telematics systems such as OnStar or Hyundai Blue Link have two-way links to service providers that relay GPS data. The operators of these services do, indeed, have the ability to see where you are, how fast you're going, and what state your car is in mechanically. They can also track and remotely disable a stolen vehicle. The Nissan Leaf uses a similar two-way connection to regularly send data on usage and location to Nissan, which the company uses for future electric vehicle development. But these services aren't supposed to work without driver permission. The car can initiate a call in an emergency situation, such as when an airbag is deployed, but otherwise the driver must authorize an external connection to the vehicle.

Companies have been caught snooping, though. OnStar found itself in the midst of a public uproar last September when it quietly changed contract terminology and started tracking customers with the intent of selling information about their driving habits. OnStar reversed the policy under pressure from consumers and Congress. Recently, insurance companies Progressive and State Farm have begun testing tracking systems, which policyholders plug into their OBD-II port. The systems record data on driving habits, and in exchange customers can potentially get lower insurance premiums, but any data collected belongs to the insurer (including any crash data).

A modern car knows where you are, is constantly tracking your driving habits, and may even be able to call for help if you crash. It's revolutionary, potentially lifesaving—and just a bit creepy. Most of a vehicle's computers are scattered around the car and carry out mundane tasks—operating the engine and transmission, windows, seats, and the radio—and these computers don't have data-storage capability (see How it Works: The Computer Inside Your Car, for a detailed tour). However, the airbag-deployment controller is a bit different. It contains a component called the event data recorder (EDR), which monitors the vehicle's network of sensors for signs of a crash and stores a few seconds of the data stream, dumping and refreshing the information constantly. The type of information collected in the EDR varies among manufacturers, but it generally includes throttle and brake-pedal position, steering angle, yaw rate (the vehicle's rotational velocity), speed, and impact-sensor data. This information is saved permanently following an airbag deployment and can be accessed through the OBD-II port by a technician using specialized equipment.

EDRs have been used since the 1990s and have recently been standardized by the National Highway Traffic Safety Administration (NHTSA)—EDRs will be required equipment on all cars beginning in 2013, with the aim of making their data easier to obtain for crash investigations. Lawyers have used this data in court cases to demonstrate driver behavior during an accident. In a Pennsylvania lawsuit related to the Toyota Prius unintended-acceleration controversy of 2009 and 2010, a team of Toyota engineers and NHTSA officials accessed the EDR of the car in question, showing that the driver was depressing the gas pedal instead of the brake, as he'd claimed.