No one will ever look at the 2010 Toyota Prius without being able to recognize it as the world's most popular hybrid car. The distinctive Prius shape, sharply defined for the public by the 2004-2009 second-generation model, hardly seems to have changed at all.

But changed it was, in ways both large and small. The 2010 Prius is more aerodynamic than ever, with a 0.25 coefficient of drag. That's as low as any car in the world that's in volume production.

Toyota's engineers moved the highest point of the roof 3 inches toward the rear of the car, offering rear-seat passengers more headroom. And the windshield is even more raked than before, with the front pillar angled so steeply forward that it almost touches the swept-back headlamps.

Flat panels on the sides of the front and rear bumpers--Toyota calls them "Aero Corners"--aid aerodynamics as well, by letting the air slide cleanly off the surface with minimal turbulence. And the rear lamps on the 2010 Prius, which were flat on the previous model, are now concave, with their top surface extending the line of the  rear deck spoiler.

The upper grille opening is tiny, improving airflow over the car's nose. And Toyota fitted the car with flat plastic undertrays to smooth the passage of air between the road and the underside of the car. It even added two flexible plastic "wings" on the underbody cover behind the rear wheels, to reduce sensitivity to sidewinds and keep the 2010 Prius tracking straight ahead.

Exterior dimensions are very close to the previous model. The wheelbase hasn't changed, at 106.3 inches; nor has the height, at 58.7 inches. The 2010 Toyota Prius is 175.6 inches long and 68.7 inches wide, adding 0.6 and 0.8 inches respectively.

And while the previous Prius could look a little like a rollerskate, with its 15-inch wheels, the new car supplements that standard size with optional 17-inch alloy wheels. Like virtually every other part of the car, they were developed specially for the 2010 Prius to improve its aerodynamics and minimize weight.

2010 Toyota Prius taillight

2010 Toyota Prius taillight

2010 Toyota Prius

2010 Toyota Prius