Like it or not, after fifteen years of inline-sixes in the M3, the time has come to move on. The E92 M3 needs to compete against the 420-hp Audi RS4, so it needs more than the previous M3's 3.2 liters of displacement. BMW says cylinders larger than 500cc are less than ideal, so it had no choice but to go to a V-8.
Luckily for purists, BMW's M Division doesn't believe in turbocharging - they feel that it just adds weight and fuel consumption. Their solution is, instead, to extract power from engines by building them to sustain speeds heretofore enjoyed only by your trusty Osterizer.
8400 rpm, that is, making it the fastest high-volume V-8 in the world. And all that revving works - the 3999-cc, 90-degree cross-plane-crank V-8 frapps out 414 hp @ 8300 rpm and 295 lb-ft @ 3900 rpm. The M3's engine is nothing more than the latest bomb dropped in the German horsepower war, landing right on top of the RS4's pretty red V-8.
To save you the time to look up that engine's numbers, we'll make those inevitable comparisons for you:
1. Last year we marveled that Audi squeezed 420 horsepower out of only 4.2 liters. BMW has now squeezed the same amount out of only 4.0. (Both engines are rated at 309kW).
2. Last year we couldn't believe the Audi V-8 revved to 8250 rpm. BMW's dyno chart doesn't stop until 8400.
3. Last year we thought it was amazing that the RS4's power peak was at a lofty 7800 rpm. That seems like peanuts, now - the M3's engine makes peak power at 8300.