The Most and Least Fuel Efficient Cars

With new fuel-efficiency standards recently mandated by Congress (see previous post), we thought we’d take a look at the mileage offered by cars currently available at your local dealer. According to the Energy Independence and Security Act, which was passed by Congress on Tuesday, Dec. 18, and signed into law by President Bush the following day, cars and light trucks, including SUVs, much achieve a fuel-efficiency standard of 35 miles per gallon by the year 2020. Of course, many cars available today already achieve that mileage — and that number will continue to grow in the years to come.

According to the U.S. Department of Energy, the most fuel-efficient car currently on the road is (ta-da!) the Toyota Prius hybrid vehicle (no surprise there). The Prius currently achieves 48 mpg around town and 45 mpg on the highway. (If we all bought Priuses tomorrow, we’d exceed the government’s mandated standard in just a few days, instead of 12 years. But why rush things?) The Honda Civic Hybrid (40 mpg in the city, 45 mpg on the highway) also already surpasses the new government standards.

But you don’t have to buy a hybrid to be fuel efficient. The MINI Cooper (37 mpg on the highway), Toyota Yaris (36 mpg on the highway), and Toyota Corolla (37 mpg on the highway) are all high achievers when it comes to fuel efficiency. Of course, those are also all compact or sub-compact cars. So will we all have to start driving tiny cars (a bummer for soccer moms and drivers with long legs)?

Heaven forbid. Many roomier cars are already close to achieving the new standards. For instance, the Volkswagen Passat Wagon, with a four-cylinder engine and manual transmission, achieves 29 mpg on the highway — it just needs a bit of a nudge to reach that magical 35 mpg goal. The Mercury Mariner Hybrid SUV, introduced a couple of years ago, and the Mazda Tribute Hybrid (pictured above), which is available this year in a limited production run of about 350 vehicles, both achieve 34 mpg, which is certainly in the fuel-efficiency ballpark.

So what are the worst gas guzzlers, according to the Department of Energy. Many are in the exotic car segment — the Lamborghini Lurcielago (just 8 mpg around town), the Bentley Azure (9 mpg), and the Aston Martin DB9 Coupe (10 mpg) are among the worst offenders. Of course, those are all 12-cylinder cars, and you probably wouldn’t jump in them to drive down to the corner 7-11 for a gallon of milk (or maybe you would).

Among the worst “normal” cars, gas-mileage-wise, are the eight-cylinder Cadillac STS (which gets 13/19 mpg in city/highway driving), the Audi S4 (13/20), the Saab 9-3 (15/24), and the Pontiac G6 (15/22). Of course, all those numbers will probably change for the better in years to come, as automakers begin to incorporate lighter-weight materials, like aluminum, rubber, and plastic, as well as carbon-fiber materials, and less steel into their cars, and seek to squeeze more gas mileage out of more efficient engines.

Also, keep in mind that the new mileage standards are fleet-wide, meaning that the average mileage of all of an automaker’s cars must be 35 mpg by 2020. That means you can still have a gas-guzzler in the crowd, as long as it’s offset by another vehicle that achieves somewhere in the vicinity of 60-70 mpg. And those cars may be showing up soon at your local dealer.