DiRT 2
This excellent new racer packs a nicely scriptable performance test. We tested at the game's "high" quality presets with 4X antialiasing in both DirectX 9 and DirectX 11 modes (DiRT 2 appears to lacks a DX10 mode). For our DirectX 11 testing, we enabled tessellation on the crowd and water.

Chalk up another win for the AMD camp. On the Radeon, pushing the resolution from 1680x1050 to 1920x1080 barely impacts frame rates and keeps the minimum FPS at a very respectable 33. You can also enable DX11 effects, although that induces a sizable performance hit. The tessellated crowd probably deserves most of the blame there.