Should we be worried that our cars are controlled by software?

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Feb. 16 2010 4:03 PM

I'm Sorry, Dave, I'm Afraid I Can't Make a U-Turn

Should we be worried that our cars are controlled by software?

Also in Slate, Tom Vanderbilt explains why bad drivers are more dangerous than bum Toyotas.

A Toyota Prius. Click image to expand.
Toyota Prius

When Toyota Prius owners take their cars to the dealer under the company's latest recall, they'll likely be out of the shop in about 30 minutes. Even though the recall has to do with a problem with the Prius' brakes, mechanics won't have to do much to fix the cars—they don't have to remove the wheels, poke around under the hood, or get near the brakes at all. That's because the flaw in the Prius is not mechanical. It's a software glitch.

The Prius, like other hybrids, uses regenerative braking—when you hit the brake pedal, it repurposes some of the vehicle's energy to charge up the car's battery. In some versions of the 2010 Prius, the code that runs the braking system is buggy. It sometimes lags before applying full stopping power. To fix the error, the dealer simply downloads and installs a new version of the software—pretty much the same routine you'd go through to fix a security flaw in Microsoft Windows.


Does this sound unusual? It's not. Modern cars are loaded with code. By some estimates, new cars contain as much software as desktop PCs, with thousands of individual functions now powered by computers. Software controls the mechanism that lets you unlock your doors, adjust your seats, and start the ignition. There's software in the powertrain—electronic components fire the sparks, determine the correct transmission gears, and constantly adjust subtle driving characteristics to optimize fuel economy. Many safety systems—airbags, speed throttlers, electronic stability control—are powered by software as well.

And like in the Prius' braking system, computers are now an integral part of what used to be the inviolably mechanical parts of our cars. Lots of cars—including the recalled Toyotas—now use "electronic throttle control," which essentially means there's no physical connection between your foot and the engine. When you hit the gas, the pedal doesn't pull a metal cable that controls the throttle, as it did in old cars. Instead, it sends an electronic signal to the throttle to let in more fuel. More advanced steer-by-wire systems will do away with the steering shaft and column. When you turn to the right, the car will send a signal to a motor to turn the wheels; in other words, your steering wheel will function pretty much like the racing wheel for your Xbox.

As someone who loves software and is often tickled by how computers have been incorporated into every part of our lives, I've got a visceral reaction to the computerization of our cars: I'm terrified. The Toyota imbroglio suggests that lots of others share my fears. The company says that it's found nothing to suggest that its electronic throttle is the cause of the sudden acceleration problem afflicting many of its cars. Instead, Toyota says, the problem involves a mechanical flaw in the pedals. But customers and safety officials aren't sure that's true. After all, how do we really know what's going on in those computers?

These fears are understandable. But they're irrational. Even though it sounds scary, integrating computers into cars brings more upsides than downsides. For one thing, cars will begin to advance at the same pace as computers. The beauty of software is that it can be updated from afar. A cell phone you buy today will keep getting better as it ages, constantly picking up new functions through downloads. Now the same will be true of cars. Through software patches, they'll keep getting better fuel economy and better safety systems. When something goes wrong, they'll be easier to fix. Events like the Prius brake recall will soon be unnecessary. In the future, your car will be able to patch itself when something is amiss, just like your PC grabs a security fix while you're asleep.

For many people, that's not a comforting thought. We don't like the thought of computers running our cars because software is opaque. We can all understand the mechanical link between a gas pedal and an engine. When a computer intervenes, though, we have no idea what it's doing. Software could also make it harder to know when something is wrong with your car. If you hear a strange screeching sound when you turn your wheel to the right, that could be a sign that there's something wrong with your steering column—you'll know that you've got to go to the shop to get it fixed (or try to take care of it yourself). But if there's only a computer between you and the wheel, you've got to trust that the machine can self-diagnose its problems—and because you don't have access to the computer, you can forget about trying to fix it yourself.



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