About half the vehicles BMW sells worldwide come equipped with four-cylinder engines, yet the German luxury car maker's single biggest market doesn't sport a single four-banger in its entire lineup. BMW hasn't sold a vehicle with a four-cylinder engine in the U.S. in over a decade, but company vice president of US engineering Tom Baloga told Bloomberg that the trend won't likely continue.

The U.S. government is mandating fuel economy averages of 35.5 mpg by 2016; a number that will shrink engine sizes for most automakers. BMW's overall fuel economy for the 2008 model year was reportedly 26.5 mpg, which means the Munich, Germany-based automaker has a lot of work to do to achieve that number. And since customers have come to expect a certain level of performance from BMW, Baloga says the company will have to increase fuel economy without hurting performance. To keep performance levels high, we expect to see more turbocharging and direct injection in future models.

Interestingly, BMW already meets 2016 U.S. fuel economy standards with its model lineup in Europe, but team Bimmer reportedly doesn't plan to fill out the bulk of its lineup with oil burners. BMW already has diesel powerplants in its 335d and the X5 in the States, though, so we wouldn't be surprised to see more diesels in the years to come.