The meanest cars for the environment in 2012

The American Council for an Energy-Efficient Economy annually hammers out a list of 12 of the auto industry's most energy-efficient vehicles and another dozen that, presumably, Al Gore wouldn't ride in if he were hitchhiking across the Mojave Desert in August.

The standouts this year include the Mitsubishi i-MIEV electric car, which displaced the council's eight-year champ, the propane-fueled Honda Civic Natural Gas. Nissan's new electric Leaf tied for second, followed by a slew of hybrids. But what about the delinquents on the other end of the scale? Here's a closer look:

Bentley Mulsanne, Maybach 57 and Bugatti Veyron

(22 points for the Bentley, 20 for the Maybach and 19 for the Bugatti … out of a possible 100; by comparison, the winning Mitsubishi scored 58 points)

Rising to the position of third "meanest car for the environment" in ACEEE's terminology, the Bugatti Veyron really can't help itself. With a top speed of 265 mph and more than 1,000 horsepower on tap from its eight-liter V16, it's actually a modern engineering miracle that the coupe can manage to get 15 miles per gallon on road trips (and 8 mpg around town). And let's be honest, this car's damage to the environment is as limited as it gets considering that at anywhere between one and two million dollars per Veyron, depending on its top configuration, these sports coupes can't be getting all that much road time. Only 30 or so are even built per year.

That can't be said for the other two rapscallions in the group, which are designed to ferry four well-heeled souls around with some frequency. Bentley's Mulsanne returns to the bad-boy list, repeating its score from last year. This flagship cruiser has a 6.75-liter V-8 helping push its nearly 6,000 lbs of heft through the air; although a sophisticated engine management system can switch off one bank of cylinders to conserve fuel, the Mulsanne still only rings in at a penalizing 18/11 mpg highway/city.

Finally, new to this continental Breakfast Club is the Maybach 57 from Mercedes-Benz, which gets 16/10 mpg. This posh 12-cylinder choice of the chauffeur-driven set has at least one thing going for it; it won't be scolded by the ACEEE for long given that poor sales - fewer than 200 of the $375,000-and-up cars sold last year - are leading to the brand shuttering next year.

Mercedes-Benz G550

(22 points)

The G550 from the folks at the Three-Pointed Star is the offspring of one of the world's first true SUVs. This military-bred machine was - along with early Toyota Land Cruisers and Land Rovers - moving people into and out of harsh terrain long before suburban moms and dads felt they needed urban assault vehicles to hit Whole Foods.

While the rest of Mercedes' family-focused line-up continues to make eco-conscious strides (note the growing range of Blutec diesel and hybrid offerings), there's really no point to making to this model (with its 15/12 mpg highway/city) an eco-warrior. Between its un-aerodynamic boxy shape and wind-resisting vertical windshield, the four-wheel-drive G550 - a simpler way to say Gelandewagen, or "cross-country vehicle" - is only going to win awards handed out by those who prize exclusivity.

Ford Expedition FFV/Lincoln Navigator FFV, Ford F-150 SVT Raptor pick-up, Ford F-250 FFV, Ford F-350 FFV, Ford E-350 Wagon

(23 points for the Expedition/Navigator, 22 for the Raptor, 20 for the F-250, 19 for the F-350 and 17 for the E-350)

This suite of Ford light-to-medium duty SUVs, four-door trucks and pickups fared poorly for a host of similar reasons, including large and thristy engines (this is six-liter territory, folks), power-consuming off-road abilities and, the enemy of any mode of transport, weight that taxes its power.

That all added up to a scolding from the ACEEE, which noted that these American-bred behemoths single-handedly nudged a number of last year's Euro-transgressors off the list, including a Bentley Continental GTC and a Mercedes ML63 AMG.

The Expedition/Navigator takes the honors as the least egregious polluter of the list's twelve violators, with the smallest engine in the group (5.4-liter V8) providing the best gas mileage at 18/13 mpg highway/city. The Raptor is essentially a high-performance, off-road-oriented version of Ford's F-150 workhorse, and as such offers mileage (16/11 mpg) that is a far cry from the most frugal F-150, a V6 that in 4x2 mode provides a more than respectable 23/17 mpg.

The more work-targeted F-250 and F-350 pay a price for weight and power (with both reporting only 16/11 mpg), but the biggest sinner in the Blue Oval bunch is the E-350 Wagon, though you might as well call it the shuttle van that takes you to the airport. With its massive 6.8-liter 10 cylinder engine (smaller only than the vicious Veyron in this group) managing a scant 13/10 mpg, this Ford never stood a chance in the council's green eyes.

Chevrolet G3500 Express Cargo/GMC G3500 Savana Cargo

(17 points)

The Express Cargo part of this Chevy's name tells you all you need to know about this class of vehicle, and why it tied with the Ford shuttle van for last place on ACEEE's list. Both iterations of this slab-sided, windowless vehicle are big sellers with global package shipping companies that troll our streets seemingly at all hours. Stuffed as they are with packages, it's no wonder that the vans need power, which they get from six-liter, eight-cylinder engines that deliver 10 mpg in the city.