My daily driver is a 1989 automatic, bought 5 years ago. Now up to 280,000 km (~174,000 miles) so.....my observations.
The youngest of these cars (such as mine
) are now 25 years old, and they ain't simple cars. Things will need to be done, and maintainance will be high. BUT, (almost) everything is still available. Be aware, you will be placing regular orders through Pelican.
Electronics are an issue, the fact that it's had some wiring redone does not concern me and if it's been done properly I'd actually argue it's a plus point. You will need to find an auto-electrician familiar with 80's European stuff.
Suspension is an issue. Basically BMW put a heavy body onto a 5 series chassis, so the suspension does suffer a bit. Bypassing the self levelling suspension is easy, and I had it done soon after I bought it. However, it's one of my regrets. Parts are available and I wish I'd kept it stock.
If you read the UK reviews, rust (esp front wings) is an issue. We don't see that so much in Australia and I suspect the big difference is use on salted winter roads.
I absolutely love driving it, it's performance is quite acceptable and they're great looking cars. I found it heavy at first, but then I did go from a motorcycle to the 635 as my daily driver, so not a big surprise. The ABS is primitive compared to modern cars and the lights are very 1980s. Get some imperial wheels, the TRX really limit you tire choice wise. E28 5 series and (from memory) E32 7 series wheels are readily interchangable and not that expensive. Don't be tempted to go for big rims, the suspension is not designed for low aspect tires and while they may look good, your kidneys will suffer.
Replace all your hoses, ALL your hoses.
My habit for repairs now is "do one, do all". I replaced the left door handle mechanism, only to have the identical part break on the right door 3 months later.
In short, great, stylish cars to drive, and actually really easy to drive. The occasional thumbs up from other drivers or compliment in a car park is a bonus.
BTW, don't be tempted by ebay parts. New parts from Pelican are often cheaper than what is been asked for on the second hand market. The Bigcoupe forum is a great trouble shooting resource.
Any questions?