I've purchased a few used cards recently and of course the dealer always claims that they've inspected the car themselves and everything is in tip top shape.

I've thought above taking the car in pre-purchase to my trusted mechanic but seems to pose some logistical issues.
-Do used car dealers actually let you have the car for that long?
-My mechanic is used booked out a few weeks in advance, so timing is a huge issue
-Do any of you actually get it checked out before buying and how did you do it?