BMW once made a secret E46 M3 CSL with a V8 engine

It’s unlikely you’ve already forgotten about it, but here it is again – BMW M is turning 50 this year. So far, they’ve already launched a couple of special edition models as well as the highly-awaited M4 CSL as celebrations, and the all-new M2 is also coming later this year – but the festivities don’t stop there.

That’s because BMW M has, for the first time ever, opened the doors to their secret M garage through a special web series on its YouTube channel, and in this first episode, we got to take a look at some of their special CSL prototypes that never made it into production – including a V8-powered E46 M3 CSL.

Indeed, that’s the E39 BMW M5’s S62 4.0-litre naturally-aspirated V8, transplanted into the E46 M3 CSL. And from the video, it seems like the engineers only just barely got it to fit inside the snug engine bay. And while the engine change reversed the 110 kg weight reduction of the CSL over the standard E46 M3, it did raise its output up to roughly 430 hp – a massive increase over the standard CSL’s 355 hp.

According to BMW, “almost no-one knows the M3 CSL V8”. And while the “crazy experiment” never made it into production, the prototype engine did eventually evolve into the S65 V8 and S85 V10 that were used in the E90 M3 and E60 M5 respectively.

Which gives us the perfect segue to the prototype E60 M5 CSL, with its 5.0-litre naturally-aspirated V10 juiced up to make 630 hp at a peak rpm of 8,750 rpm. Yes – the massive V10 in the prototype actually revved close to 9,000 rpm.

That in itself is already madness, but it’s also the first car in BMW’s stable to use the Getrag seven-speed dual-clutch transmission (DCT) rather than the clunky SMG gearbox (if you – for some reason – did not opt for the manual). The same gearbox later went on to be used in the E90 M3 and other subsequent M cars.

And last but not least, is the E63 M6 CSL prototype, which helped BMW opened the doors to active aerodynamics. While not much has been done to its drivetrain, the M6 CSL prototype here has been fitted with an electronically-controlled front splitter and rear spoiler, which makes the M6 “very stable” at speeds starting from 110 km/h.

Much of the interior trim have been replaced with lightweight material in line with the ‘L’ in CSL (which stands for lightweight). And the unique BMW M wing mirror covers with the wing on top? That was developed here on this prototype M6 CSL model.

There are apparently more CSL prototypes that we haven’t seen just yet, including a F87-based BMW CSL. That will come in the second episode, and we already can’t wait to see (and hear) it.


  1. Hello everybody,
    Just to inform you that you made a mistake concerning the e39 m5’s S62.
    It’s not a 4.0 litre but à 5.0. (4942cm2)

    Thank you for this nice article


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