It has a 5 speed manual gearbox, which I've told providing it's not had a hard life are pretty much solid??
if its a 1995 model then I take it its the 3.0.
These are pretty much bullet-proof engine and the vanos' are pretty much trouble free compared with the 3.2's.
Service history is a must, I would also recomend you do a HPI on it.........you'll be surprised how many M3's have been wrapped around a lamp post- Check the shut lines on doors, boot and the bonnet, make sure all looks right and straight- just because nothing shows up on a HPI doesn't mean its not been hit.
The gearbox's on these are pretty much solid aswell......but you may get kind of a rattle or chatter when switching the car off........don't be alarmed, this does'nt mean that its buggered, this is just one of the cars characteristics I'm afraid.......but if you hold the clutch in and then turn the car off- you wont hear it...........its normal.
just listen out for the usual knocking noises from the rear when driving and engaging gears.........the engine should sound smooth and not tappety- if it does then ask the owner if he/she knew when the valve clearances were checked/adjusted last.......if they dont know then you could be looking at around 200-250 squids to get that done........that will quieten the engine down.
Look for any excess vanos noise- "growl".........its ok to get a certain weird growl from the engine upon startup for a second or two- thats just the vanos unit..thats normal...don't worry about it but if the noise persists and is intermitant while you are driving then you have a problem and Vanos' are not cheap..........but again, not come across 3.0 vanos failures to be honest.
If yours a coupe then they are prone to ECU damage in the way of water getting down into the DME and VNC compartment in the bulk head.
.........that's it really as far as the 3.0's go...........then of couse the obvious like make sure the car doesn't go over the halfway mark on the temp gauge.......they always stay smack in the middle........always check the car from cold.....old beemers have issues when cold-if its been warmed up then be suspicious but don't wack the owner over the head....it may be their daily driver.
Also may be worth checking when the O2 sensors and cat was changed if at all depending on the milage- if the cats been changed then make sure it was with a genuine part......if it was aftermarket then be warned- those are totally crap, never fit right, sound awful, they have smaller cats and piping on them and will strangle some horses from the car......and the dam things sit too low so you'll forever be having trouble with speed bumps and ramps.