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07-16-2026LAST POST
Recently sold my pristine E85 Z4 3.0si and had wanted to replace it with an E86 Z4M, but looking at other options now since finding one and at the right price, seems to be tricky. All my life, I’ve been in love with 3 BMW models: E31 850i, E39 M5, and E86 Z4M. I see myself owning one of these as a forever garage queen, savoring every minute invested in working on it. It won’t be always garaged - I’m buying it to drive and enjoy.

If it comes down to an E31 850i (manual) vs E39 M5, which would be the better forever BMW? Better in appreciation? Keeping it runnning? I will never say no to the M5’s performance, but an E31 shines in its own way. Any advice is appreciated.
E39 M5 will probably be easier to source parts, they are awesome cars.

E31, I have driven and maintained an 850i auto. Has steering box which felt more loose to me, kinda floaty even for a BMW. Not really fast, the E39 M5 felt much faster, revved more freely. Might be a long way off from a Z4 in terms of handing, weight, and quickness.

The M5 also has a steering box but the one I drove was very tight even at 100k miles, unlike the E31 with less miles, might be car specific according to wear and mileage.

I would probably recommend M5 overall, manual E31 would be fun for sure and maybe better investment due to rarity? I recommend test driving one first, I found the E31 to be more "vintage" in terms of handling and power, where the E39 M5 felt modern but still exciting.

Good luck, have fun!!
I would buy the E39 M5 over any E31. Z4M if you never need to carry 3-4 people and want a more direct and involving car, but you already know that. Since you have had a long run already with a Z4, try something different.
Here's what I think: as soon as I see an 850i, 850Ci, or 850CSi, the first thing that comes to mind is I hope you're ready for high maintenance. If you want a queen and don't care about what it takes to take care of her, then the 850CSi and only the CSi takes the cake. But if you want something that's not going to have you on your knees, then the M5 100%.
Not just maintenance intervals but the part sourcing and costs too for E31, a big job in and of itself, so many fewer E31s were made.

Engine stuff wasn't too bad but body and interior parts can be very difficult to find,
If it’s forever, what does resale value matter? :lol:

The E39 M5 is easily the answer to your question though.
E39 M5 all day long.
Its got to be the M5 E39, a no brainer really.
Thank you all for your input. The consensus here is def. the E39. I kind of assumed as much, but the thoughts around E31's looks and rarity kept intruding on my decision.
*with a muffler delete

Can't beat the S62
M5 and keep your Z3.
spielnicht wrote
Thank you all for your input. The consensus here is def. the E39. I kind of assumed as much, but the thoughts around E31's looks and rarity kept intruding on my decision.
While I understand the rarity of the E31, when it comes to repairing and parts cost $$$, then you will kick yourself for not getting the E39.
The general council at my company had a 850csi, manual, dinan stroker. No parts are available, so keeping it on the road is a massive pita.

And remember the csr was conceived as a gt, not really a sports car like a z4m
If you want to drive it hard and feel connected every time, get the E39 M5. It’s the better “driver’s” car and easier to live with.
If you want something unique, beautiful, and more of an event to drive, get the E31 850i 6-speed. It’s a grand tourer in the truest sense, and you won’t see another at every cars and coffee.

For a forever garage queen you actually drive, I’d lean E39 M5 because you’ll use it more without dreading the next repair bill. But if you fall for the E31 shape and the V12 mystique, nothing else scratches that itch.

Have you driven both? That usually answers it instantly - the E31 feels like a concept car you can drive, the E39 feels like the best 4-door sports sedan ever made.

What’s more important to you: the drive, or the “I own a piece of BMW history” factor?
Very well said, very clearly outlines the differences between the cars..
JamesBMer wrote
If you want to drive it hard and feel connected every time, get the E39 M5. It’s the better “driver’s” car and easier to live with.
If you want something unique, beautiful, and more of an event to drive, get the E31 850i 6-speed. It’s a grand tourer in the truest sense, and you won’t see another at every cars and coffee.

For a forever garage queen you actually drive, I’d lean E39 M5 because you’ll use it more without dreading the next repair bill. But if you fall for the E31 shape and the V12 mystique, nothing else scratches that itch.

Have you driven both? That usually answers it instantly - the E31 feels like a concept car you can drive, the E39 feels like the best 4-door sports sedan ever made.

What’s more important to you: the drive, or the “I own a piece of BMW history” factor?
SYT_Shadow wrote
The general council at my company had a 850csi, manual, dinan stroker. No parts are available, so keeping it on the road is a massive pita.

And remember the csr was conceived as a gt, not really a sports car like a z4m
Elderado82 wrote
Here's what I think: as soon as I see an 850i, 850Ci, or 850CSi, the first thing that comes to mind is I hope you're ready for high maintenance. If you want a queen and don't care about what it takes to take care of her, then the 850CSi and only the CSi takes the cake. But if you want something that's not going to have you on your knees, then the M5 100%.
TriumphTim wrote
Not just maintenance intervals but the part sourcing and costs too for E31, a big job in and of itself, so many fewer E31s were made.

Engine stuff wasn't too bad but body and interior parts can be very difficult to find,
These are typical comments from people who have never owned one. The truth is far different. I’ve owned three, and currently still have two - a ‘96 850Ci, and a ‘94 850CSi. I’ve owned the ‘96 850Ci for 24 years, and the 850CSi for eight. I drive them regularly, have had no problems keeping them on the road, and the maintenance is no more costly or problematic than most M cars (and probably less). And they put an ear to ear grin on my face every time I get behind the wheel.
Lol, nice flex, but not really understanding the point I was making, stupid stuff like window switches on an E31 are a pain to source if needed.

OP should understand that kinda stuff if buying anything less than a top notch example in perfect working order. It is a fact that many less E31s were produced so less parts supply and support in general, more E39 parts will carry over from base to M.

OP is coming from Z4s, the E31 is pretty far from that.

Also, have you driven an E39 M5? They really are a superior driving experience in every way.
TriumphTim wrote
Lol, nice flex, but not really understanding the point I was making, stupid stuff like window switches on an E31 are a pain to source if needed.

OP should understand that kinda stuff if buying anything less than a top notch example in perfect working order. It is a fact that many less E31s were produced so less parts supply and support in general, more E39 parts will carry over from base to M.

OP is coming from Z4s, the E31 is pretty far from that.

Also, have you driven an E39 M5? They really are a superior driving experience in every way.
I understand your point; you just aren't as informed as you think. While some parts are in fact NLA, a surprising number are still available. Both the V12 and V8 engines used in the E31 were used in many other BMWs, so most mechanical and maintenance parts are still readily available.

Additionally, the E31 community is practically a cult, and very helpful. The forum on Bimmerpost is incredibly active with folks sharing information about used parts, rebuilding parts, parts cars, and the increasing number of businesses that are making new parts that can't be purchased from the dealer. And I'm not talking just about little things like window switches. How about fuel pump assemblies, dash vent assemblies or cam shafts? I have never run into an issue where I couldn't get a part I needed. Are they cheap? Sometimes yes, sometimes no, but then M parts aren't cheap either.

Have I driven an E39 M5? No. But I'm not trying to say the the E31 is the best BMW ever (although I do think it is one of the best looking BMWs ever). But I have driven several different M-cars, and enjoyed them all. I own an F80 M3 and the 850CSi (which is also an M car). They are all fun to drive in their own way - as are non-M cars. My Z4 M40i FE is a hoot to drive, as is my X7 M60i. The sales manager at my local dealership used to say you could get in trouble in anything BMW sells. We should all find what makes us happy and enjoy it. But if you are going to warn someone against ownership of a particular model, please make sure you are correctly informed before spreading negative information that may unfairly dissuade someone from finding what could make them happy.
E31 upkeep just too much. what everyone is saying here is correct. sourcing parts is super difficult.
stbm5 wrote
E31 upkeep just too much. what everyone is saying here is correct. sourcing parts is super difficult.
Sigh. Have you tried, or are you just parroting what you’ve heard other people say? If you have an E31 and are looking for something, let me know what you need and I’ll be glad to help.
Sorry you are taking the E31 criticism so hard but I am not sure you do understand the point, you are confusing me with other posters.

I clearly stated most engine and maintenance parts are doable just the chassis specific stuff can be expensive.

The OP needs to understand that new OEM E39 dash vents are $215 while aftermarket E31 vents are $679, can you confirm quality?

An E31 NOS drivers side window switch is $1200 on ebay, used ones are $400.

I am not making a judgement simply stating facts, if the OP has the passion for the E31 go for it, just be prepared.

Feel free to provide actual data to argue whatever point you are trying to make, like total miles driven since purchase versus maintenance costs. I couldn't care less but you may actually help the OP make an informed decision? Or maybe have your BMW sales manager chime in for you?



mbarrett635 wrote
I understand your point; you just aren't as informed as you think. While some parts are in fact NLA, a surprising number are still available. Both the V12 and V8 engines used in the E31 were used in many other BMWs, so most mechanical and maintenance parts are still readily available.

Additionally, the E31 community is practically a cult, and very helpful. The forum on Bimmerpost is incredibly active with folks sharing information about used parts, rebuilding parts, parts cars, and the increasing number of businesses that are making new parts that can't be purchased from the dealer. And I'm not talking just about little things like window switches. How about fuel pump assemblies, dash vent assemblies or cam shafts? I have never run into an issue where I couldn't get a part I needed. Are they cheap? Sometimes yes, sometimes no, but then M parts aren't cheap either.

Have I driven an E39 M5? No. But I'm not trying to say the the E31 is the best BMW ever (although I do think it is one of the best looking BMWs ever). But I have driven several different M-cars, and enjoyed them all. I own an F80 M3 and the 850CSi (which is also an M car). They are all fun to drive in their own way - as are non-M cars. My Z4 M40i FE is a hoot to drive, as is my X7 M60i. The sales manager at my local dealership used to say you could get in trouble in anything BMW sells. We should all find what makes us happy and enjoy it. But if you are going to warn someone against ownership of a particular model, please make sure you are correctly informed before spreading negative information that may unfairly dissuade someone from finding what could make them happy.
spielnicht wrote
Recently sold my pristine E85 Z4 3.0si and had wanted to replace it with an E86 Z4M, but looking at other options now since finding one and at the right price, seems to be tricky. All my life, I’ve been in love with 3 BMW models: E31 850i, E39 M5, and E86 Z4M. I see myself owning one of these as a forever garage queen, savoring every minute invested in working on it. It won’t be always garaged - I’m buying it to drive and enjoy.

If it comes down to an E31 850i (manual) vs E39 M5, which would be the better forever BMW? Better in appreciation? Keeping it runnning? I will never say no to the M5’s performance, but an E31 shines in its own way. Any advice is appreciated.
Damn that’s a lot