Turn the cap and leave it in place with the engine running. It should kind of dance around a bit not blow off. Watch for blue smoke when over running downhill and coming to a stop. If it does there is too much blowby. The 2.5 NA seem prone to burning oil but the 2.5 turbo does not seem to have this problem. Put the trans in park then shift into reverse and start counting one thousand two thousand three thousand. If you get to three before it clunks into gear the trans is wornish. Watch for a flare on each shift , a slight increase in engine speed before it clunks into gear It takes a while to build up pressure but not that long. Look for oil residue or black crud in the rad overflow tank a sign of head gasket problems, Look for rusted out rear jacking points. look under the battery for significant rust. Check all windows actually go up and down, Check that power seats go every which way they should both sides of the car. check that climate control actually controls the fan speed, check that the AC compressor actually kicks in when you punch the defrost button actually look under the hood to see it working. Check that the sunroof opens and closes evenly with no misalignment of the panel. check the electric locks work from all the doors and the trunk. Check that it only has one key for all the doors. Check that the body gap on all doors and the hood and trunk are evenly spaced. Check the back door handles actually work from the inside and outside. Check the drivers rear seat mounts to the body for signs of rust. Check that the heater actually works and is not bypassed. Check the passenger footwell for signs of leaking antifreeze actually lift the carpets on both sides of the front seats to look for rust or coolant. cover the end of the muffler with you hand or a rag to see if it builds up pressure. When you drive the car try out the cruise to see it works and smoothly.
I have been burnt by everyone of these suggestions some are more expensive to fix than others. It shouldn't take more than 10 mins to check them all. Print this list and check off as you go. Owners may not be sure of things or they may not want to reveal that they do know what is wrong. I prefer to verify for myself rather than taking someones word for anything.
Cheers and good luck,

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It's always something simple
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