You think a Mini cooper is small? Ha! A third of Japanese drivers buy kei ("light") cars, which are so compact, owners get a special permit to park free in crowded cities. Kei are 11 feet long, 6.6 feet tall and 4.9 feet wide-or less-and legally limited to 660cc's and 63 horsepower. (They're longer but narrower than Smart cars.) Until now, the vehicles were simply shrunken versions of bigger models. But Mitsubishi designed its new "i" model from scratch to make the safest, roomiest and most high-tech kei yet.

BMW's M-cars have always thrilled drivers, but the new M6 is one of the best ever. Its 5.0-liter V10 pumps out a none-too-shabby 394 horsepower during relaxed driving, but hit the power button-an automotive first-and it will light up the rear tires with 500 horses. To squeeze out even more performance, BMW added variable valve timing and pushed the redline up to 8,250 rpm, then matched the engine to a seven-speed, paddle-operated sequential manual gearbox. It's 4.6 seconds to 60 mph, but sadly, the car is electronically governed to 155 mph. $100,000 (estimated)

For its new Civic Hybrid, Honda engineered a gasoline-electric powerplant that's more powerful (110 horsepower, up from 93) and fuel-efficient (50 mpg city/highway). To increase the torque and horsepower from the 2.8-inch-thick electric motor, engineers cleverly swapped the round wire in the motor's armature for a flat one. That switch let them cram more wire in, increasing the power density. During deceleration, when the electric motor becomes a battery-charging generator, the variable-valve-timing system seals the gas engine's cylinders.

Large engines are taxed heavily in Japan, a crowded country that offers few opportunities for speed, so don't look for a 500-horsepower Lexus anytime soon. But that doesn't mean Japanese powerplants don't pack a punch. In fact, Japan exports the engine that produces the most power for its displacement: The Honda S2000's 2.0-liter 4-cylinder makes a remarkable 240 hp without supercharging or turbocharging. It simply spins faster.