Workaround
I had the same problem (also crashes halfway through the benchmark). Apparently the current version of the 650M driver doesn't support all the PhysX functionality used in Arkham City.
Until nVidia release a new version of the driver, the workaround is to go into the nVidia applet in Control Panel, and under the "Set PhysX Configuration" item, select the CPU as the PhysX processor...
Then it seems to be fine. Even manages almost playable framerates at native 2880x1800 res (with AA disabled as redundant on retina of course 🙂 )