Most Power-Packed Cars

It's the biggest disconnect in the auto industry: Though government, scientists and consumers all call for cleaner, higher-mileage vehicles, that green chorus can still be drowned out by the roar of a V8.

Hybrids and alternative fuels are gaining a foothold, but the early 21st century has also brought an unparalleled golden age for powerful internal combustion cars. The most potent muscle cars of the '60s look positively shriveled compared to today's high-tech machines that put out 600 horsepower or more.

Despite volatile gas prices and massive publicity for hybrids, fuel economy is still not top-of-mind for most buyers. In a 2007 study by J.D. Power, nearly 100,000 car buyers ranked fuel economy as only their eighth-highest priority, trailing not only the leading issue of reliability, but also vehicle performance and image.

In Pictures: Most Power-Packed Cars

In a U.S. market that moves 16 to 17 million cars a year, there are more options than ever for Prada-loafered leadfoots who just want to burn up the road and blow away onlookers — and if they have to stop every 200 miles to fill up their thirsty beasts, so be it.

Large-scale sedans and coupes from the likes of Bentley and Mercedes-Benz may bristle with muscle, but horsepower alone doesn't always win the race.

Rulers of The Road

As drivers and engineers have always known, the true measure of a scary-fast car is its power-to-weight ratio: A 300-hp sports car at a svelte 3,000 pounds (or one horsepower to motivate every 10 pounds) will whip a 4,500-pound sedan with the identical engine, because the sedan saddles each horsepower with 15 pounds. And it's not just about straight-line force; lighter cars tend to stop quicker, change direction more readily and carry more speed through curves, which is why racing leagues handicap too-speedy entrants with extra weight to even out the competition.

So with a nod to Mother Nature and Father Physics, our top 10 list ranks cars that combine crushing power with the slimmest weight. To keep things simple, we've expressed the ratio in pounds-per-horsepower: All things equal, a car with a lower number will pack more punch.

Not surprisingly, today's most power-packed rides are sports cars that put a premium on weight-saving construction. These are, for the most part, carbon fiber, aluminum or steel-tube space frames, and titanium and exotic alloys. The 505-hp Chevrolet Corvette Z06 employs a titanium exhaust system and sandwiches balsa wood between carbon-fiber layers to create a floor that's strong but featherweight.

Such materials are not only expensive, but often require specialized manufacturing that adds even more cost. The result is fanciful rides that can shred the budget of the typical enthusiast. Some, like the Saleen S7 and Mosler MT900S, are essentially endurance racers, tweaked just enough to legally prowl the streets.

Our power-packed list is limited to street-legal production cars that have been certified to meet U.S. safety and emissions standards — which leaves out stripped-down screamers like the Ariel Atom.

Finally, there's still more to ultimate performance than power and weight: Tire traction remains a key factor, which is why the all-wheel-drive Bugatti Veyron wins a drag race against the only cars that outrank it in power-to-weight ratio: Sweden's Koenigsegg CCX and the American Saleen S7, whose rear-drive layouts prevent them from applying as much power to the pavement before their tires spin and smoke.

The Bugatti's improbable top speed also spotlights the importance of sheer horsepower and aerodynamics. A car must not only slice through the air but also generate hundreds of pounds of downforce to remain stable and avoid lifting off like a plane run amok . Here again, it's the 1,001-horsepower Veyron, with its special key that must be toggled to safely exceed 233 mph — the body hunkers down, while spoilers and air inlets adjust Batmobile-style to create optimal aerodynamics — that the company claims has hit nearly 254 mph.

We didn't see that speed during our test drive, but whipping the $1.4 million Veyron through the Connecticut countryside did raise a question: What exactly is the fine for speeding 200 mph above the limit? Test any one of the cars on our list, and you are bound to find out.

In Pictures: Most Power-Packed Cars