Race Driver GRID
I tested this absolutely gorgeous-looking game with FRAPS, as well, and in order to keep things simple, I decided to capture frame rates over a single, longer session as I raced around the track. This approach has the advantage of letting me report second-by-second frame-rate results.

The 9800 GX2 is fastest overall, but it wasn't without its quirks. I had to copy in a new SLI profile file in order to get GRID to use both GPUs. Once that was installed, the GX2 obviously did very well. On a similar note, the Radeon HD 3870 X2 seems to have lacked a profile for this game, since it wasn't any faster than a single 3870.

One oddity in the numbers is that the GTX 260 seems to be bumping up against a frame rate cap at 60 FPS most of the time. Only once, during a short period, does it reach above 60. I'm not sure what's going on here. I tested and re-tested, confirmed that vsync was disabled, and the results didn't change. My best guess is that the GTX 260 might be interacting with some sort of dynamic level-of-detail mechanism in the game engine. Interestingly, the GTX 280 rarely ranges below the 60 FPS level.