About a year ago we brought you a report that BMW was looking at a four-cylinder 3-series for American sale, but that was at the height of the fuel-price crisis, and since then talk of the efficient BMW four-bangers has died down. A recent report has breathed new life into the idea, however, and once again fuel efficiency lies at the root of the plan.

Speaking with Bloomberg, BMW's top North American engineer, Tom Baloga, said that the four-cylinder may be the best solution to meeting higher fuel economy standards without seriously impacting performance - a key aspect to a marque that bills itself as the 'Ultimate Driving Machine'.

BMW competitor Mercedes-Benz has also been considering going four-cylinder for the U.S., going so far as to unveil a four-cylinder diesel E250 BlueTEC Concept at the New York Auto Show this year. So far no hard plans have been announced, however.

With even the BMW M brand considering four-cylinders - and the U.S. is the primary market for the M Division - it's clear that change is coming. The questions are when will that change come, and how will it take shape? The 3-series is a likely candidate, but the 1-series might be a better first step, especially since vehicle footprint is taken into account in the new fuel standards. Even the X3 is a possible candidate for a four-cylinder, as markets outside the U.S. already get such a vehicle.

What do you think? Do four-cylinders belong in performance-luxury cars? Should a turbocharger be a mandatory inclusion? Or is a diesel four-pot enough to satisfy the thirst for fuel economy and performance in an affordable package?