In proper tune, you should get 29-30mpg, but that depends on the condition of the trans, as well. Listen for a rattle from the SC at idle. The coupler rattles only at idle when worn, but it'* a cheap and relatively easy fix. Look for a light coating of dust on the engine, showing that they didn't clean it to hide something.
After it'* idled, check the trans fluid. Make sure it'* good and pink. Other than that, the normal checks for any car. The SSEi drivetrain is pretty much bulletproof if basically maintained, but the trans is a potential weak spot.