While some of us here at ABG HQ are major fans of BMW's diesel engines, we were disappointed when BMW opted to enter the U.S. market only with the twin turbo 3.0-liter six cylinder diesel. As fantastic an engine as that is, the 2.0-liter four cylinder is also plenty strong and yields even better fuel efficiency. At an event at BMW's North American headquarters this week, VP engineering Tom Baloga told the audience that BMW would introduce the four-cylinder diesel to the U.S. lineup now that tougher fuel economy standards have been imposed. In keeping with BMW's performance image, we will get the more powerful variants, likely the dual turbo, 204 hp version used in the 123d rather than the super-high-efficiency versions. Even with that engine, we averaged 37 mpg in the 123d last year. BMW plans to clean up the four cylinder diesel with a lean NOx trap like VW uses for the Jetta and Golf TDI rather than a more expensive and complex urea injection system. The four cylinder will most likely go into the 3 and maybe 1 series cars with the six being reserved for larger cars like the 5, 7 and X5.