BMW E31 850i V12 — buying guide and what to expect in 2026

Owned an E31 850Ci for 4 years now. Absolutely love it but you need to go in with eyes open. Here is my pre-purchase checklist:

1. Compression test on all 12 cylinders — non-negotiable on the V12
2. Check for coolant in the oil (head gasket issues on M70)
3. Inspect the pop-up headlight motors — replacements are 800+ EUR each
4. Test the automatic climate control — the blend door actuators fail and the dashboard needs to come out to replace them
5. Check the ZF 4HP24 gearbox (auto) for harsh shifts — rebuild costs 3000+ EUR
6. Inspect the rear subframe mounting points for cracks — common on E31
7. Check all window regulators — the frameless doors put extra stress on them

The 840Ci with the M62 V8 is honestly the smarter buy for someone who wants to actually drive the car regularly. The V8 is more reliable, parts are cheaper, and it still looks identical from the outside. The V12 is for collectors and enthusiasts who do not mind spending money on maintenance.

From a mechanic perspective, the E31 is one of the most complex BMWs to work on. The engine bay is incredibly tight, especially on the V12 — simple jobs like spark plug replacement take 3-4 hours because of access issues. The wiring harness is also a concern on 30+ year old cars — the insulation becomes brittle and shorts can cause all kinds of phantom electrical issues.

For the M70 V12, the EML (Electronic Motor Load) throttle system is unique to this engine and finding someone who can properly diagnose it requires specialist knowledge. The Bosch Motronic 3.3 ECU is no longer repairable by BMW — you need a specialist like BBA Reman or a good auto electrician.

If you find a clean example with documented maintenance history, buy it. These cars are only going up in value. The 850CSi with the S70 engine is already in supercar money territory and the regular 850i/Ci will follow. Just budget 3000-5000 EUR per year for maintenance and you will be fine.