Do a search on here for Z3 Buyers Guide and you should get some links to old posts to have a look through
View: https://www.youtube.com/watch?v=m_5ebx5Olv8 Thought this was a fair and accurate buyers guide for the Z3 and may be of help for any potential buyers. Zorg even gets a mention ;) ;)
zroadster.org
Always do an MOT check and see what its test history looks like before you go and view the car, then you are in a position to check if any fails or advisories were dealt with. Rust in the cover sills needs checking, you can't see the inner sills until the outer cover ones are removed but if the inners are rusty its not for the feint hearted to tackle repairs. The outer cover sills are easy they just bolt on like all the other body panels. Check out the condition of the rear suspension and subframe for rust and holes in the trailing arms and condition of all the rubber bushes. Check the engine for oil leaks around the cam cover and the joint between the oil filter housing and the engine block, gaskets fail at these points. All rubber hoses and plastic pipes across the engine should also be checked, no holes or splits in any of them. I would also plug a code reader in to the car and check for any codes. If the seller won't allow this, walk away, might be hiding something.
Usual visual checks on wheels and tyre condition and watch the exhaust for smoke when started. Always best to do a cold start and let it warm up keeping an eye on the tailpipe for smoke whilst you continue with your visual checks over the car. Test drive to check clutch and gearbox, listen out for rattles and knocks and bearing noises. Check the interior carpets for water underneath the carpets there is thick foam under them that can get waterlogged from leaks into the car. Check the operation of the roof powered or manual and if it works. Check the dash for any warning lights. When the ignition is turned on you should see the oil light and the airbag light, upon starting both should go out, if any remain then code read it as fault codes will have been set indicating where the fault is.