I think Audi's RS4 V8 would be a good contender, only it was in the same bracket as the M5's engine... oops. 0.2 liters less, and it could have clobbered the M3's engine (which is still good... but nowhere near as impressive as that V8).

The Renesis isn't as impressive as the Twincharger... even though it's more reliable than old rotaries, it's a wonder in this day and age to see an engine that needs to drink oil to keep from overheating. The Twincharger, on the other hand, produces 2.0 power while still maintaining excellent fuel consumption.

I'd have picked Mazda's 2.3 direct injection turbo over the Subaru, but, oh well...

I'd like to know what the criteria are, and who came up with the segments. It's not an even representation, methinks. Shouldn't there be a section for economy engines and for performance engines? And mass-market as compared to expensive engines? The only engines there that aren't on expensive cars are the Subaru 2.5 and the VW 2.0, and even then, the term "cheap" or "economy" doesn't exactly apply to them.