07 SS Cobalt (supercharged)
 

Make sure the intercooler pump is working, open the small coolant cap at the front of the engine while it's running and see is the coolant is moving. Look for rust at the bottom of the doors. If you can lift the car up check for broken rear coil springs and torn rearward control arm bushings on the front control arms. Check for any rattling from the timing chain on cold start. Other than that just ask about general maintenance stuff. Hopefully others will chime in here on anything I may have missed.

I'd also pay particular attention to the front ends on these cars, they are garbage from the factory. When I bought mine at 55,000 miles it was so loose it was squirming like an eel under any acceleration, pulling on every rut and line in the road, and would hop like an SOB if the tires got loose. After two front end rebuilds it's finally good. The first rebuild lasted about 50,000 miles – which I babied it for. All it took was about 15 miles of bad road to knock all the joints loose at the end of its life, though. I ended up having the factory joints replaced with Moog joints for the second rebuild and they've been tough as nails so far (knock on wood).

The head was also a major issue for my car. It's had two replacements and the head gasket was partially blown when I had it replaced for an oil leak because that's the only way the part that was leaking was available. Otherwise, the engine's been pretty rock solid. Unless you count the TPS failure recently.

To be fair to the car, the people that owned it before me treated her pretty rough.