BMW is considering using its four cylinder engines in the US for the first time since 1999 to meet tougher fuel-economy standards, according to Tom Baloga, the company's vice president of engineering for North America.

He told Bloomberg News BMW needed to improve fuel efficiency without hurting its reputation for performance vehicles. He added: "The biggest challenge will be maintaining the 'Ultimate Driving Machine' performance."

Carmakers must boost industry-wide average fuel economy to 35.5mpg by 2016 under US rules adopted in May that moved up the deadline by four years. Bloomberg noted that BMW would find it harder to meet the new standards than most companies because it has a smaller vehicle range and focuses on compact, powerful models.

Baloga said BMW's fleetwide average was 26.5mpg in 2008. Exact increases for individual automakers have not yet been set because the government is still writing the new standards.

Baloga did not say when BMW might offer I4 engines once more in the US. About 50% of the company's models worldwide use them in models such as the 1- and 3-series as well as the X3 SUV and one of its 5-series cars.

BMW's European line-up would already meet the US standard for 2016 because 67% are diesel-powered, Baloga added. It has two diesels in the US; the 335D sedan and a version of the X5 SUV.