ide just note the milage down/take a picture with the time stamp on a camera.
if it comes back with anything more than 10 miles or so on ide start questioning it, as said though, sometimes they need to drive it to see if the problems fixed.
someone i used to work with had his lasses car in a garage, rang up a few days later and they were saying they had to order parts in and would be a few more days, when he got it back he was noticing it was crabbing across the road a little, then noticed some of the panels werent matching up properly and were slightly different colour, went back and asked about it, after a while he found out that one of the lads had taken it out and crashed it, then tried to repair it by replacing panels ect. but he missed the bent chassis making it slightly drift accross the road! car was a wright off and the garage owner said he would not pay out however would fire who ever it was who crashed it and they would have to pay him back, noone would grass him up so noone got the sack and he didnt get any money. think he was on about taking them to small claims court but havent seen him for a while so dont know whats happend with it.... safe to say that garage lost a customer
