BMW M’s Secret Garage Houses Some Insane One-Off Prototypes

These never before seen BMW M cars will definitely make you drool

When the BMW M4 CSL debuted earlier this year, it was only the third M car to ever wear the CSL badge throughout BMW M’s 50-year history. Prior to the M4 CSL, only two have been blessed with the CSL badge, and these include the (E9) 3.0 CSL and the (E46) M3 CSL. That’s because weight shedding has been the main driving point of all CSL (which means Competition, Sport, Lightweight) vehicles, but did you know that four more CSL cars were actually almost put into production?

E46 BMW M3 CSL V-8

BMW M's Secret Garage Houses Some Insane One-Off Prototypes
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And what better way to start this article than by talking about the E46 M3 CSL that we see here. What sets this M3 CSL apart is the fact that it’s not fitted with a 3.0-liter straight-six. Instead, this comes with a unique S65VB40 4.0-liter naturally-aspirated V-8 that produces 424 horsepower. While the production M3 CSL saw a weight loss of 110 kg (242 pounds), this V-8 prototype slightly gained a bit of weight back due to the heavier V-8.

BMW M's Secret Garage Houses Some Insane One-Off Prototypes
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This one-off E46 M3 CSL was mainly a testbed for its future V-8s, and the lessons gained from developing this engine eventually carried over to future M vehicles. As a matter of fact, the S65B40, a derivative of this engine, went into production in the E90 BMW M3, which produced 420 horsepower.

E60 M5 CSL V-10

BMW M's Secret Garage Houses Some Insane One-Off Prototypes
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The E60 BMW M5 CSL became a testbed for a bigger 5.5-liter V-10 that produced 630 horsepower and had a redline of 8,750 rpm. It came with a weight loss of 150 kg (330.7 pounds) thanks to the carbon roof, the addition of Recaro front seats, and the removal of the rear seats. In addition, the M5 CSL came with a double-clutch transmission (DCT) instead of the single-clutch semi-manual gearbox (SMG) in the standard M5.

BMW M's Secret Garage Houses Some Insane One-Off Prototypes
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Setting the E60 M5 CSL apart from the standard M5 include the additional air inlet below the kidney grille—which was meant for the oil cooler for the transmission, and the forged 18-inch wheels. Along with fine-tuning the suspension, the M5 CSL was able to lap the Nürburgring in just 7 mins 50 seconds. Despite this, the M5 CSL was never green-lit for production.

E63 M6 CSL V-10

BMW M's Secret Garage Houses Some Insane One-Off Prototypes
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Whereas the two other M CSL prototypes served as test beds for future engines, the M6 CSL came with active aerodynamics. As a CSL, it came with reduced weight (but at an unspecified amount) but it also came with a deployable front spoiler under the front bumper and an active rear spoiler. If you’ve seen the "Doppelsteg" side mirrors of BMW M cars today, you also have the M6 CSL to thank for that.

F87 M2 CSL

BMW M's Secret Garage Houses Some Insane One-Off Prototypes
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While not yet explained in the video, the BMW M2 CSL was briefly shown at the ending. A BMW M2 CSL was actually supposed to be produced, and it came with the same upgraded 450-horsepower 3.0-liter straight-six from the M2 CS. What made the CSL different from the CS were its racing bucket seats, roll cage, carbon fiber center console, carbon fiber rear wing, and carbon ceramic brakes.

The M2 CS was also being developed during the same time as the CSL, but only the CS went into production due to the former being more suitable for daily use. The M2 CSL remained a one-off.

Source: BMW M

Isaac Atienza
Isaac Atienza
Isaac Atienza is a Filipino motoring journalist who joined TopSpeed.com in 2021. He is a car enthusiast who especially thinks that wagons are the best type of vehicle, though sports cars and anything with three pedals also tickles his fancy.  Read full bio
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