The Least Fuel-Efficient Vehicles of 2007

The least fuel-efficient car on sale in the U.S. is Lamborghini's ultra-expensive, all-wheel-drive Murcielago LP640. This is largely due to the car's reworked 6.5-liter V12 engine ***

Being very heavy, yet very fast, the 2007 Bentley Arnage is no fuel-sipper. At about 5,700 pounds, the standard R version of the luxury sedan runs from zero to 60 mph in 5.5 seconds, courtesy of a 450-hp 6.75-liter V8 engine. The Arnage T trades some refinement (very little) for flat-out speed with a boost in power to 500 hp, while the stretched RL version is heavier and fares the worst of the three variants in terms of fuel economy. ***

Ferrari boasts that its all-new 599 GTB Fiorano has the highest performance of any V12 production car it has ever built. With 620 hp, the 6.0-liter engine moves the 599 GTB Fiorano from a standstill to 62 mph in 3.7 seconds. Top speed exceeds 205 mph, useful for quick trips to the gas station. ***

This four-seat Ferrari gives little ground to its smaller two-seat siblings in speed or in fuel consumption. The Scaglietti boasts a 5.75-liter V12 engine and has a 28.5-gallon fuel tank, allowing the car to motor more than 350 miles between fill-ups. As a "grand touring" (or GT) sports car, the front-engine, rear-drive 612 Scaglietti offers more luxury and comfort than other Ferraris but is by no means as plush as a Bentley or even a BMW. ***

Available since spring 2006, the latest Azure convertible is Bentley's premier model, exceeding its siblings in price and excessively opulent appointments. But the Azure does share its deep thirst for gasoline with other Bentleys. This high-roller's "drophead," as the say, is based on the stately Arnage sedan (also on this list) and shares its front end, suspension and running gear while using two doors instead of four. ***

Chrysler, which owns Dodge and Jeep, likes to make fast trucks. In 2006, the Dodge Ram SRT10 pickup truck was the most profligate fuel user on our list. This year's DaimlerChrysler entry is a juiced-up Grand Cherokee stamped with the company's "SRT" logo (for Street Racing Technology). The "8" in SRT8 indicates the number of cylinders in this SUV's 420-hp 6.1-liter V8 engine. With a zero-to-60-mph time of less than five seconds, Chrysler advertises the SRT8 as the fastest Jeep ever made. ***

Like some of the other conspicuous fuel consumers on this list, the Bentley Continental Flying Spur manages to be both very heavy and very fast. Bentley puts the all-wheel-drive Flying Spur's curb weight at just under 5,500 pounds. Its 6.0-liter, twin-turbocharged V12 produces 552 hp and accounts for the Spur's high top speed of 195 mph. ***

We rank the Mercedes-Benz ML63 AMG (pictured above) and R63 AMG together because both SUVs guzzle fuel at the same rate by virtue of having the same engine and transmission: a 503-hp V8 that cranks out 465 pound-feet of torque and is attached to a seven-speed automatic. AMG is Mercedes-Benz's subsidiary charged with creating super-fast derivatives of regular models. ***

Priced under $200,000, the Gallardo is Lamborghini's entry-level car. Though it may not guzzle gas as quickly as the more potent Murcielago LP640, no one will call the ninth-ranked Gallardo fuel-conscious. Both coupe and convertible models have a 5.0-liter V10 engine that puts out 500 hp. The droptop Gallardo Spyder is heavier, and therefore it burns fuel slightly faster. ***

The DB9 is the smallest, lightest vehicle and offers the best gas mileage of the least fuel-efficient lineup. But its 450-hp 6.0-liter V12 engine is built for speed rather than efficiency: The DB9 jets from zero to 62 mph in 4.9 seconds. This quintessential British sports car comes in two versions, a hardtop coupe and convertible Volante. ***