The top gas guzzlers of 2007

By Dan Lienert

updated 4:09 p.m. ET May 2, 2007

When it comes to the market's least fuel-efficient cars, what costs us cash at the pump also draws stares at the stoplight.

Consider Ferrari's recently released 599 GTB Fiorano coupe, which is priced at around $250,000.

The car has a 620-horsepower, V-12 engine. It is Ferrari's most extreme performer — basically a street-legal race car — so of course it burns fuel like a 747, getting 11 miles per gallon in the city.

Ferrari probably expects the vehicle to be on a list of gas guzzlers, and most likely doesn't care; economy is not the point of the 599. Nor is it for another of the market's least fuel-efficient cars, Lamborghini's 12-cylinder Murciélago two-door, which costs around $290,000 and gets nine mpg in the city.

Our list of the least fuel-efficient 2007 model cars, according to recently released data from the U.S. Environmental Protection Agency (EPA), includes such other beauties as DaimlerChysler's $390,000 Maybach 62 luxury sedan and BMW's $100,000 M6 hot rod.

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But not all fuel-inefficient autos were included. That's because it's early into the 2007 model year, and the EPA has not yet published fuel economy figures for all cars.

For example, General Motors' notoriously wasteful Hummer H2 doesn't appear because the EPA has not yet issued the car a 2007 model ranking. And because of varying fuel economy estimates from different sources, we chose the EPA as the official — and only — source for data in this story.

What's more, we only included autos with their original equipment — no vehicles modified by others after they rolled off assembly lines are on the list. For example, we did not look at the customizations that California's Saleen makes of Ford Motor's Mustangs. And in evaluating a model's ranking, we only considered one entry per nameplate: the least-efficient one.

For example, we included BMW's 6 Series line of coupes and convertibles, but that's because the M6, the flagship of the 6 Series line, gets 12 mpg in the city. We did not look at the other, more-efficient models within the 6 Series family in formulating our list.

We ranked the vehicles in our story based on what it costs to fuel them per year, according to the EPA. In calculating a car's annual fueling cost, the EPA assumes you will drive it 15,000 miles per year. The EPA also takes into account the current price of fuel. For this story, average first-quarter fuel prices were used to estimate the annual cost.

We measured cars by fueling cost because the EPA lists two gas mileage figures per car, city and highway mileage, and we did not want to make an arbitrary decision about which mileage figure is more important. When you buy a car, your daily driving routine will determine whether city or highway mileage is more important for you.

While hard-core sports cars and opulent luxury cars tend to have bad mileage, some of the vehicles on our list are old, heavy models with inefficient engines. Chevrolet's $23,000 Express van, which is tied for fourth place on our list, is one example.

But you might be surprised by another leading cause of bad mileage: ethanol fuel, an alternative to traditional gasoline.

Many American cars are able to run on both gasoline and ethanol. But ethanol is less energy-dense than other fuels, so it reduces fuel economy by 25 percent to 30 percent. Many of the cars on our list — particularly the American cars — can run on ethanol or gasoline, and the ethanol-powered cars tend to be less fuel-efficient than their traditional counterparts.

But in some cases, the vehicles on our list are simply there because they are SUVs or pickups that use big, powerful and, yes, inefficient V-8 engines.

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