The 10 Least Fuel-Efficient Vehicles

By Jeff Zygmont

Sure, this lineup includes some low-slung racers that run so fast they make you stammer. But our listing contains some surprises as well, beginning with the very first, most fuel-thirsty entry.

All of these vehicles travel rather fast, and some are inordinately heavy. A few are deliberately lightweight. That fact may seem to contradict our fuel-use equation (more speed plus more weight equals more fuel). But you have to consider that the manufacturers of outer-boundary sports cars trim vehicle weight not to gain miles per gallon but to divert more engine power and hence more fuel, to the speed side of the equation.

By necessity, our ranking includes only 2006 model year vehicles rated by the EPA. Yes, that's most everything. But the agency does not gauge the fuel use of what it calls special-purpose vehicles. That group includes the two big Hummers, H1 and H2. Without comparative data, it's impossible to say if either model would make the Top 10. But regarding H2, Peter Ternes, Hummer's director of global product communications, reports that "our engineering team is experiencing an average performance of about 12 miles per gallon under normal driving conditions, commuting to and from work." If 12 mpg was an official, EPA-certified fuel-consumption rating, H2 would certainly earn a place among the 10 least fuel-efficient vehicles of ?06.

What?s more, the 2006 Fuel Economy Guide does not include some heady racers that are still available as ?05 models. The Ferrari 575M Maranello, for one, ranked number six on last year?s list of least fuel-efficient cars. At 12.41 miles per gallon, it would have retained a spot on the current ForbesAutos.com 2006 list if Ferrari had produced an ?06 model.

Finally, keep in mind that measuring fuel efficiency in terms of miles per gallon is only a popular convention. You can also compute efficiency as the power per gallon a car strains out of gasoline. By that measure, these bottom 10 all land near the top.

Dodge Ram SRT-10
Rank on 2006 Least Fuel-Efficient List: 1
Vehicle Type: pickup truck
Price: $47,605
Miles Per Gallon: 10.56
City/Highway Miles Per Gallon: 9/12 with automatic transmission; 9/15 with manual
Fuel: premium gasoline
Estimated Annual Fuel Cost: $4,403

Comments: You drain fuel fastest with either excessive weight or outlandish speed. The 2006 Ram SRT-10 embraces both vices, making it the biggest fuel hog on record. This super-size pickup weighs more than two-and-a-half tons. Yet with its 10-cylinder, 500-horsepower engine, it sprints from zero to 60 miles in just over five seconds. In 2004, it won acclaim as the world's fastest production pickup in the Guinness Book of World Records, sustaining a speed of 155 miles per hour for a full kilometer. Mercifully, the SRT-10 accommodates a fuel tank the size of a bathtub. Its 26 gallons gives the pickup a cruising range greater than the distance between you and the next filling station. For drivers who control their testosterone, Dodge sells versions of the Ram pickup with smaller engines, and therefore greater fuel economy. The most conservative, with a 3.7-liter six-cylinder, gives you 18 miles per gallon.

Bentley Arnage
Rank on 2006 Least Fuel-Efficient List: 2
Vehicle Type: midsize passenger car
Price: $216,270
Miles Per Gallon: 11.47
City/Highway Miles Per Gallon: 10/14
Fuel: premium gasoline
Estimated Annual Fuel Cost: $4,054

Comments: It lacks an open pickup bed in the back, but the 2006 Bentley Arnage seems to take a cue from the beefy Ram SRT-10: It is very heavy, yet very fast. In fact, at about 5,700 pounds (in its smaller configuration), Arnage weighs more than a quarter-ton more than the Ram but is slightly slower. The Arnage T ? the speediest version ? runs from zero to 60 in 5.5 seconds. Its 6.75-liter, twin-turbocharged, 450-horsepower engine pushes the luxury cruiser to a top speed of 168 miles per hour. Arnage R and the long-wheel-base Arnage RL trade some of that power for greater refinement. Its 6.75-liter engine is tuned to deliver 400 horsepower, accelerating from 0 to 60 in 5.9 seconds in the Arnage R, 6.0 seconds in the RL. Both versions are electronically speed-limited to 155 miles per hour. The stretched RL version is 10 inches longer and about 150 pounds heavier than the other models, but it still earns the same 11.47 miles per gallon fuel-economy rating.

Ferrari 612 Scaglietti
Rank on 2006 Least Fuel-Efficient List: 3
Vehicle Type: four-seat midsize sports car
Price: $247,850
Miles Per Gallon: 12.67
City/Highway Miles Per Gallon: 10/17 with automatic transmission; 11/17 with manual
Fuel: premium gasoline
Estimated Annual Fuel Cost: $3,670

Comments: The twin-passenger rear seat is a distinguishing characteristic of the 2006 612 Scaglietti. But the four-seat Ferrari gives little ground to its smaller two-seat siblings in speed or in fuel consumption. It uses a variation of the 5.75-liter V12 that powers the 2005 Ferrari 575M Maranello. The Scaglietti version develops more horsepower, reaching a peak of 540. At just over 4,050 pounds, Scaglietti also weighs about 250 pounds more than the two-seat Maranello. Yet Scaglietti manages to eek out one half-mile more per gallon in fuel economy. With a 28.5-gallon fuel tank, it can motor more than 350 miles between filling stations. As a grand touring sports car, the front-engine, rear-drive Scaglietti takes greater pains to provide creature comforts. For example, Ferrari promotional material notes that door size and even hinging accommodate easier entry and egress, while backseat leg room and head room are substantial.

Aston Martin V12 Vanquish S
Rank on 2006 Least Fuel-Efficient List: 4
Vehicle Type: two- and four-seat midsize sports car
Price: $255,000
Miles Per Gallon: 13.08
City/Highway Miles Per Gallon: 11/17
Fuel: premium gasoline
Estimated Annual Fuel Cost: $3,555

Comments: Aston Martin makes much of the fact that V12 Vanquish S, with a 520 horsepower, V12 engine, is the fastest production car the company has ever made. It is faster than cars made by a lot of other companies, as well. V12 Vanquish accelerates from zero to 62 miles per hour in a mere 4.8 seconds. If you stay on the accelerator pedal it will reach a top speed that exceeds 200 miles per hour. You can buy Vanquish as a two-seater, or, optionally, as a two-plus-two touring version. Like the Ferrari Scaglietti, V12 Vanquish is not a feather-light speedster. Instead it loads in some lavish amenities to make motoring comfortable. At 4,144 pounds, the V12 Vanquish essentially matches the four-passenger Scaglietti in weight. To keep it from growing heavier, Aston Martin makes Vanquish from aluminum, tailoring each body panel around a center structure by hand. The method ensures a tidy fit, the company crows.

Bentley Continental Flying Spur
Rank on 2006 Least Fuel-Efficient List: 5
Vehicle Type: midsize passenger car
Price: $164,990
Miles Per Gallon: 13.33
City/Highway Miles Per Gallon: 11/18
Fuel: premium gasoline
Estimated Annual Fuel Cost: $3,488

Comments: 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. That makes it only about 200 pounds lighter than its more profligate sibling, Bentley Arnage, the second least fuel-efficient vehicle in our ranking. But the Flying Spur surpasses the beefier Arnage in flat-out speed. It reaches a top end speed of 195 miles per hour, compared to 168 for the Arnage. Its zero to 60 miles per hour pace of 4.9 seconds is more than a half second faster than the fastest Arnage version, Arnage T. Although the Arnage T carries a larger engine, the 6.0-liter, twin-turbocharged V12 in the Flying Spur produces more horsepower ? 552 compared to 450 in the Arnage. That helps account for the Spur?s faster feet.

See the rest of the list from ForbesAutos.com here:

6. Aston Martin DB9
7. BMW M5
8. Maserati Quattroporte
9. VW Phaeton W12
10. Ferrari F430