Firemint has put up the above video tech demo of their Real Racing game running optimized for an iPhone 3GS and.... wow.

“Since the game uses a high fidelity physics engine, adding cars is a good test for pushing the hardware. We started our tech demo with 8 cars on the track, then 10, 12, 16 and 20, and the 3GS still didn’t break a sweat,” wrote Firemint’s Alexandra Peters. “We finally stopped when we got to 40 cars on the track at the same time, still with no perceptible drop in frame rate. We think the results are mind blowing.”

No plans to release an iPhone 3GS version yet but again, that's a switch that some developer will no doubt throw at some point.