[Law]

Originally Posted by Son of Achilles

2009 E60 M5 CSL

For newer folks or those with shorter memories, this was a one-off M GmbH production made to celebrate the 25th Anniversary of the BMW M5 (German: 25 Jahre M5).

It featured a 5.5L V10 (theoretically an "S85B55") good for 580 HP mated to a 7-speed DCT and lightweight construction, including a carbon fiber roof and featured other goodies like a carbon fiber intake plenum (the noise!).



What a machine and a shame they didn't put it in production (though I'm sure the M engineers would've loved to)

Come to think of it, most of those BMW M prototypes (i.e., E46 M3 Touring, E31 M8, E34 M5 Convertible, E39 M5 Touring, X5 LM etc.) belong in this thread but my favorite and one that also hasn't been mentioned is the E31 M8.



It's my favorite BMW they never made because the story of the car has been a sort of urban legend and folk tale for BMW fans. No other BMW has this kind of mystical legendary allure. Cars like the E30 M3 are legends because of what we know about them. But the E31 M8 is a legend because of what we didn't know and still don't know about it.



It was and is clouded in so much secrecy yet so revered with awe and it's the only one of the 'what if' BMWs (outside of a modern M1) that you can't build yourself, no matter how much money and resources you may have.



Its pedigree is connected directly or indirectly to BMW Motorsport history, the 1999 BMW victory at Le Mans, Team BMW/Schitnzer Motorsport, the McLaren F1, Paul Rosche, and more...even though it didn't even officially exist until 10 years ago.



The E31 M8 prototype comes with a spec sheet and bloodline that would make the modern M8 a plebeian and unworthy of the nameplate by comparison.



It had a naturally aspirated V12, related to, or similar to the one that powered the McLaren F1, with individual throttle bodies with carbon fiber intakes and intake runners, mated to a 6 speed manual in a body constructed with lightweight materials.



Since this one-off prototype shrouded in so much mystery and obscurity, for decades, most people (and the internet) thought for the longest time that it either did not exist or that the prototype was destroyed in the 1990s...that is until it resurfaced in the summer of 2010, still in the collection of BMW M's now famous 'secret underground garage'.



Partially thanks to this obscurity, there are many versions and conflicting accounts regarding details of the actual V12 engine in the M8 prototype.
We know the S70B56 powered the E31 850CSi...and few know that it was actually a true M GmbH engine and the 850CSi even bore the chassis VIN prefix "WBS" in authentic M fashion, meaning it is a full-fledged M-car/product just not badged as such.
But it lacked individual throttle bodies or a sophisticated (compared to other contemporary motorsport units) cylinder head being an SOHC (24 valve) design and a block that was a slightly massaged M70.
We also know that the S70/2 is the famous V12 that powered the McLaren F1 and that the S70/3 (aka P75) was the racing version that brought BMW that famous 24 Hr Le Mans victory in the V12 LMR.
So what about the M8 Prototype?



The most accepted and most widely propagated version that circulates the internet over the years is built upon years of rumors and insider knowledge, an amalgamation of urban legend and forum talk...BMW at one point even acknowledged and tried to clear up some of it...but nonetheless it says that there is a 550 HP 6.0L V12, the S70/1 that was allegedly bespoke to the M8 Prototype. Most of the press articles and reports also echo this.



However, BMW recently published their own article about the M8 Prototype, further adding to the confusion and mystery.
In the BMW article, they claim official specs from the S70/2 variant, which would make it identical to the BMW V12 in the McLaren F1, except the quoted horsepower figure at 640 HP, is even higher than the standard McLaren F1.

This contrasts with the long line of previous knowledge and reports that always cited 550 HP from approx. 6000cc of displacement.



So either BMW made a typo, or they don't recognize the existence of the S70/1, or everyone was wrong all this time.
I guess we'll never really know.
But it doesn't really matter...because the key takeaway is that the E31 M8, a lightweight coupe of a brilliant design with a manual gearbox and an NA V12 pushing 550-640HP is the best BMW they never made...and a strong contender for the best car of all time that they never made.