I have always had very cheap cars so like ford fiesta, micra etc. For the first time, I am looking to get a better car. One I am looking at is a BMW Z4 E89 2 door 2.5 23i sDrive. This is from a private seller. I will be honest, I don't know much about cars. One advantage about having a dirt cheap car was I didn't have to care much about maintenance, any mechanic could basically do it. My friend is saying that Z4 is a limited model car as in I would struggle to get parts and they will be expensive if things don't work. Is this concern valid? Does Z4 have reliability issues?

Also he scared me that it's not smart to get it from private seller as he knows people that somehow lower the mileage before selling! So basically he is saying just buy from large traders like Big Motoring World etc. Thing is I have always bought from private sellers in the past but unlike this one my previous cars were mostly under 1K lol. The car in question is 66K miles and has had 5 owners. How can I make sure that service history I am shown is genuine and things like mileage haven't been tampered with?