1991 BMW 850i - learn me

I saw on of these for sale locally. I like the looks. What is the scoop on these? I've never owned a V-12. I know it's an automatic. How are these in terms of maintenance/cost/parts availability?

I don't know the specific answers to tout questions, but I can tell you one thing you may not know.
Those cars are simply gorgeous!! Now you know

These infamously have two ECUs, one to control each bank of cylinders individually like a straight six. They are awesome cars but big, heavy, and full of every early 90's BMW luxury doodad known to man. Prices range from about $6k to $25k in my experience because it takes a LOT of money to make one right when it has problems. Rough ones typically have nightmarish electrical problems. BMW has always been great about parts availability but it doesn't come cheap.

I would love one someday but personally I'd start with an 840i and do the 6-speed swap, or maybe put bits from a wrecked E39 M5 in. The V12 sure sounds awesome but really doesn't have a whole lot of advantages outside of the cool factor. Many disadvantages like awful engine maintenance when it needs to be done, abhorrent gas mileage, etc. But if you HAVE to have a V12, it is there. Not fundamentally unreliable but very sensitive to maintenance. They are not very fast either but cool tourers for sure.

I love them but unfortunately I know to many former owners that hated them to know that I need to stay away from them.

That v12 was designed for the 7 series with the goal of good fuel economy at 150mph on the autobahn.

Fortunately that is a super awesome design requirement, unfortunately getting more than about 330 HP out of the motor takes serious custom work.

It's 5.0l, sohc, aluminum, 60deg v angle. But the heads are unique and the exhaust port is bad for high flow.

Parts from 7 series with the same motor are incredibly cheap on the used market because no one wants to try to touch a 25 y.o. broken 7.

Also, the CSI 850s did come with a manual. Rare, but available.

In reply to Robbie:

You could also get a plain 850i with the 6-speed manual, believe it or not. Uncommon but they are out there. The CSI has some additional performance upgrades and BMW M trim parts without being a "true" M car.

pointofdeparture wrote: In reply to Robbie: You could also get a plain 850i with the 6-speed manual, believe it or not. Uncommon but they are out there. The CSI has some additional performance upgrades and BMW M trim parts without being a "true" M car.

This sounds blasphemous but having owned one the automatic is a better car and at the end of the day more reliable. Some of the manual parts and NLA and basically some breaks are a death sentence for the car. DK motors are seriously expensive to fix correctly, the car needs the two batteries in the trunk to be matched and in perfect shape for it to run correctly.

At the end of the day for what you are spending a newer 5 series is the better car, but the 8 looks better. Mine had 160K miles when I sold it and I once added up all the repairs from the previous owners that were in a book in the trunk at around 47K USD since new. But most of that was labor and cosmetic parts like the rear speaker covers and tracking down electrical problems and DK motor replacement twice on both sides.

In reply to wearymicrobe:

The 5-series isn't immune either...I went through the MDK fiasco on my '99 528it. There is only one to replace but it's still an expensive and seemingly unnecessary repair to swallow. If I own another BMW it will have as few electrical doodads attached to the engine as possible. Crap like VANOS, the MDK, etc always ends up being more trouble than it's worth.

I've seen two in person my whole life. They were in the same junkyard complete if that gives you any idea. Both 850's

My ex has a serious want/love for these so we spent a fair bit of time researching them. She spent time talking to club members and met a few at a club meeting at the Carlisle Import some years ago. At the end of if all, she basically figured out that until she can afford to spend top-dollar on a well kept one, an 8-series will have to remain a dream. As much as she hates automatics, she was also told the car is really more suited to one.

Also, around the same time, we did a light restoration of her parents' mid-80's 300SD and she got an eye-watering education of what it takes ($$$$) to keep an older German car that isn't used enough in top condition. I'm sure that also dulled her desire for an 8 a bit.

A blasphemous idea I have to buy a non-running one, rip out the electrics and re-wire it with a Painless kit, drop in an LS/auto drive train and build 180 deg headers for it to disguise the swap a bit.

I'm with DrBoost. The car is gorgeous and that's all I know. Appreciate the insight from everyone so far.

Megasquirt and done.

beans wrote: Megasquirt and done.

Aaaand the intake manifolds are tubular, so chopping off the plenum and going with 12 carbs or itbs from a motorcycle would be easy!

It's the automatic transmission computer integration I would worry about.

From the couple of people I've known with 850s, they don't break much if they're cared for. But they can be $$$ when they do break.

Robbie wrote:

beans wrote: Megasquirt and done.

Aaaand the intake manifolds are tubular, so chopping off the plenum and going with 12 carbs or itbs from a motorcycle would be easy! It's the automatic transmission computer integration I would worry about.

oh god, trying to tune 12 carbs and sync them sounds like an absolute nightmare.

The V12, itself, isn't bad. All the parts bolted to it make it expense when it does wrong.

POD and Weary already mentioned the "two of everything" and absurdly expensive DK bits. Other things like trim pieces/panels are now NLA and treated as gold (headlight motor/assembly ~$1200 used).

The underpinings aren't complicated, but have a ton of wear items (bushings). Think of the suspension as an E32/E34 front and pre E38 rear.

A ratted example would cost a ton to get right. Atl had some decent V12 examples from $8-16k a few years ago. The V8 version is nearly as fast and a bit newer. Swaping one to a manual is also easier (420g trans a WAAAAAY cheaper and readily available than the V12 unit), but the aftermarket has adapters to use the ZF six cyl manual trans with the V12. The pedal box is closely related to the E34 piece.

I believe dyintorace had a 840 . . . Maybe he will chime in as well.

I don't know much personally but my bmw friends aren't big on the way they drive and they can be an electric nightmare

Friend of mine had one, complete money pit and not a lot of performance. I love BMWs (have had 4) but wouldn't touch an 850 with someone else's ten foot pole.

In reply to markwemple:

I keep hearing that from Bimmerphile about how the 8'er drives. They also point at the car being heavy. At 3900-4200lbs, it's no heavier than the beloved E38. The recirc and ball steering does make it numb and slow, but the car is design the eat miles, cross contients, and look good while doing so . . .

I can agree with the electrical nightmare statement

Says a lot whrn the Porsche 928 is preferred. The 928 is a great GT but when things go wrong, they can go very wrong.

Robbie wrote: Also, the CSI 850s did come with a manual. Rare, but available.

C&D said that it sucked and you're better off with the automatic.

C&D. Said don't get the manual.

I gotta drive one just so I can experience it. Supposedly the clutch travel was incredibly long and the shifter feel was trucklike.

Maintenance parts for the V12 are absurd in price. I remember something like $1000 in parts just for an ignition tuneup. I have no idea why because in theory it's just two times the six cylinder bits. Anyway he scrapped the car rather than fixing it.

The 928 GTS may still be the best GT you can buy.