[KNS]

Z3 came in four cylinder and six cylinder engines (not sure if the four cyl was sold in the US). The M52 and M54 inline sixes are the same engines used in the E36 and E46 3 series models and are very long-lived engines. Many of the maintenance items for the E36 and E46 can be found on the Z3.

James May from Top Gear drove a Z3 four cylinder automatic in one episode and hated the transmission but didn't have anything bad to say about the rest of the car.

Their biggest weakness (like many BMWs), are the plastic cooling systems. Look for comprehensive records of cooling system maintenance. Also, control arm bushings are good for about 60,000 miles. By this age there should have been a lot of work performed overall unless it was a sunny day driver with low miles. I've owned an E46 for 20 years and am very happy with it. Never driven a Z3.

E46fanatics.com covers a lot of maintenance for the 3 series and you'd find a lot of similar maintenance covered there. Not familiar with the most popular Z3 sites.