A pair of BMW Sevens

    With BP's well still spewing oil into the Gulf of Mexico, energy policy and the importance of fuel economy are on everybody's mind.

    Automakers are ahead of the curve on this topic, as they race to meet strict mileage standards coming due in 2016.

    The new standards weigh especially heavy on makers of German luxury cars, who have typically emphasized performance and technology over fuel economy.

    But they are taking the new standards very seriously. Mercedes will be introducing a hybrid-version of its flagship S-class the next time it redesigns the car.

    In a less radical move, BMW, which dines out on its V-8 engines and the occasional V-12, is returning a six-cylinder Seven-series car to the U.S. for the first time since the 1992 model year.

    The 2011 740Li weighs 200 pounds less than a 750Li and is powered by a 315-horsepower inline six vs. a 400-hp V-8 in the 750LI.

    Despite the smaller engine, the 740 is quick enough for most purposes, getting to 60 miles per hour in 5.8 seconds vs. 5.1 seconds for the 750.

    And the 740 gets much better mileage: 17 miles per gallon city/25 mpg highway vs. 14 mpg city/mpg 21 highway. A tank of gas will carry you 543 miles in the 740 vs. 456 miles in a 750.

    Virtue is not the only reward you get for choosing the 740. Its sticker price is $10,000 less than the 750. While the as-tested price of my imperial blue metallic approached $100,000 (including a $1,000 gas guzzler tax), the titanium silver metallic came in at a slightly less unreasonable $89,025.

    Both cars looked great, drove well, and contained more electronics than I could understand without having a degree in electrical engineering.

    The Seven's exterior styling has been refined (and looked better in the silver of the 740 than it did on the dark blue 750), and the interiors were warmer than in past BMWs, which have flaunted black-on-black color combinations that would warm the heart of a funeral director.

    Which car would I buy? It goes against all my instincts, but if I were going to indulge in a Seven-series BMW, I would choose the 750. It felt slightly livelier and less imposing, despite its weight.

    But in the end, it comes down to the following: Don't scrimp if you want to splurge. If you need to own a Seven-series and feel the need to be kind to the environment too, leave it parked in your driveway and use a BMW motorcycle as your daily driver.