Driving toward a more livable planet

Kids, the world is counting on you to change America's driving habits.

Scientists say that Earth's climate is slowly, slowly heating up. Exhaust from cars and trucks is seen to be a major cause for this. Meanwhile, most American adults are still comfortable driving big honking sport-utility vehicles that guzzle gasoline.

Not me – at least not today. I'm test-driving a Toyota Prius hybrid car. As I whiz along the freeway, keeping up with 70 mile-per-hour traffic, I'm getting 52 miles per gallon – twice what the typical new car gets.

I pull off the highway. Arrows on a computer screen in the center of the dashboard begin switching back and forth. The computer is telling me that my car is using more battery power and less gas.

At a stoplight, the gasoline engine, spookily, abruptly stops. My car is silent. But I can still hear the throbbing engines of the cars around me. (Hmph. Old technology.)

When the light turns green, I step on the accelerator. The gas-powered engine starts up instantly. Had I started more slowly, the gas engine would not have come on at all. Instead, the car would have moved forward with a high-pitched whine, sounding like a loud electric train set. That's the sound of battery power.

Hybrid cars have four driving "modes": electric power only, gas power primarily, battery charging, and braking. A computer under the hood switches among modes automatically. Hybrid-carmakers figure that trend-setting drivers who buy hybrids will want to see what mode the car is in – thus the dashboard display.

Critics say driving a hybrid car is no fun. They're slower than gas cars. But hybrid owners like Courtney Cole of Illinois say they are fun to drive – but in a different way. Her husband, Casey Hayward, likes to play fuel-economy games. How high can he get the gas-mileage readout to go while he's driving?

An electric motor linked to the gas engine in a hybrid not only can run the car, but also can provide extra power for climbing hills or acceleration. It restarts the gas engine quickly when traffic lights turn green.

The motor has another function, too: When electricity is flowing through it, it can drive the car. But when the electric motor is being turned by the momentum of the car, it generates electricity. This electricity is used to recharge the hybrid's batteries.

That is the key to hybrids' high gas mileage. When you step on the brake in a conventional car, your forward motion is turned into friction (heat energy) by your brakes. You're throwing away energy! Hybrids, on the other hand, can recapture some of that forward momentum by using it to generate electricity and storing the electricity in batteries.

Hybrids also use less gas because they have smaller gasoline engines. The electric motor provides the added power needed.

But not all hybrids have to be small or slow. Next year, Ford will introduce an SUV hybrid. A few years later, Honda (which builds the other two hybrid cars being sold today) wants to market an expensive sports car and a luxury sedan that would use the extra electric power not for fuel economy but in order to go fast.

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