Check the bottom of the windscreen for milkyness, water penetrates the laminates at the bottom and it progresses up the screen. Not too much of a
problem but can be used as a bargaining tool against the seller. New windscreen is the only cure, then wait for it to start again in a few years time.
Turbo "Owl or Police siren" noise. If it sounds like you're being followed by a copper a few hundred yards behind, don't worry too much as most of them do this. If it's like he's right behind you or there's an owl in the engine bay, walk away.
Check inner edges of the rear tyres for wear. The rear axle geometry is critical and if set incorrectly causes inner edge wear and also sounds like a rear wheel bearing away.
Make sure the radio gets a good signal. Try it on the AM frequency as well, and if you can't get any AM stations very well, then the aerial is goosed. Cost about £30 is for a new base and antenna, and an hour to replace yourself.
Check the rear lights are working correctly. The side lights and brake lights are the same single filament bulb, just fed with different voltages for each, and the terminals inside the fitting corrode away. If one side is slightly brighter than the other, then there's a
problem with the connection. Can be replaced with a part from the
dealers, but more ammo for you.
There'll probably be more but I've just got in from work.