the Z3's are pretty good cars. off the top of my head i can't really think of a whole lot of problems with them. the biggest problem i have ever herd of is people that just simply don't drive them enough and the battery can go dead, vut that is a common issue with any car that is only driven for a couple months out of the year. the drive train and the suspension is very similar to the E46 which are also great cars. one problem that is more of a BMW problem is the lower ball joints they can get worn out and have to be replaced. the engines are awsome they have minimal issues. one thing that is a common issue with some people is that the rear window can get cloudy on the convertibles, whcih is all Z3's. but some people just deal with the cloudy plastic and others replace them just depends on your budget and preference i guess. but all in all they are good cars and are a lot of fun to drive also.