In an interview with Gameplayer, Rick White from Volition said they’ve pushed the Xbox 360 as far as they can.

Gameplayer: So you’re saying that RFG is pushing the hardware as far as it can go? Squeezing every drop of juice out of the Xbox 360?

Rick White: Yeah, we’ve got it to the point where we can’t even put an extra vehicle into a world, because it’ll blow the memory. Every little change we make we have to be hyper-critical about it because it could just bring the whole system down. We evaluate every little change in the game, and then we run our tools on it to make sure it isn’t going to break the game and then we move forward, so it really is about pushing the engine as far as we can, and pushing the hardware as far as we can, and then looking at what is the next set of hardware that’s going to come out. Where can we take it then? You know we’re already thinking about if we had XYZ X number of years from now, what would we do with our engine?