Although the next generation M3 is still about three years away, speculation has already begun about what engine configuration will power it. The current generation is blessed with the wonderful S65 V8, but there's been word the next M3 will return to the six-cylinder engine due to emissions regulations. Perfect example: the upcoming M5 will have a bi-turbo V8, instead of the V10. However, BMW M is reportedly testing four different engines for the next M3.

They include: 1. S65 V8 Bi-Turbo. Say what? Really, as it turns out, BMW engineers have reworked the engine internals, lowered the redline a bit, and added a bi-turbo. Output would be higher than the current S65, but torque would be much higher with less fuel consumption. 2. Modified N54. Biggest advantage: lower production costs. Pitfalls: Not powerful enough. 3. Modified S63. The upcoming F10 M5's twin-turbo V8 could fit into the next M3, but BMW is hesitant to do a "one size fits all" approach.

4. V6 Engine Based on the S63. Supposedly the current favorite. This is a V6 based on the S63 V8 turbo. The number of turboss remain unknown, but this engines makes for better weight distribution. Only downside is that it's a V6, which could upset many BMW fans. Remember, this is all speculation at this point, but BMW is certainly looking at numerous options.