The time has come. BMW is planning to bring its European four-cylinder diesel engine to the U.S. market. They haven't yet said which American market models will get the diesel mill, nor exactly when it will debut.
The engine will be the 181 hp 2.0-liter four banger currently available in the European 320d. Putting two and two together, we would guess that it will probably become available in the 2012 BMW 3 Series.
BMW claims its 320d gets 57 mpg under fancy European conditions, so the new Bimmers could give Volkswagen's fuel thrifty models some real competition when converted to American.
(Hat tip to teampenske3!)