What's all this about?
This is the BMW M4 CSL, the most hardcore, track-focused (yet still road-legal) version of the M4 so far. It’s a substantial 100kg lighter than its nearest stablemate, the M4 Competition, and has an extra 40hp under the bonnet. The CSL “has track driving as its raison d’être,” according to the company and is being launched as part of BMW’s Motorsport division’s 50th birthday celebrations. The name, CSL, stands for “Competition, Sport, Lightweight” which pretty much sums up the car.
Lightweight?
OK, so a kerb weight of 1,625kg might not be Lotus Elise territory, but the CSL has managed to save a significant 100kg over the M4 Competition by embarking on a crash diet. Body panels such as the roof, bonnet and boot-lid are made from carbon-fibre reinforced plastic (CFRP) which saves 11kg. Saving another 24kg are the full carbon bucket seats, while getting rid of the rear seats and seatbelts loses an extra 21kg. Cutting back on the soundproofing and using lightweight insulation saves 15kg; the titanium rear silencer reduces the weight of the exhaust system by 4kg, and small changes to the grille, rear lights, floor mats and the climate control system save four more kilos.
Any work on the engine?
The CSL uses the same 3.0-litre, twin-turbo six-cylinder engine found in the rest of the M4 range (including the M4 GT3 racing car) as the base from which to work. The boost pressure on the turbos has been turned up, with the engine management settings adjusted accordingly. To help the rest of the engine cope with the power and torque boost, there’s a forged, lightweight crankshaft, and the cooling and oil supply systems have been upgraded to handle track use. The exhaust system has also been acoustically engineered to create a loud “racing car-inspired” sound.
More power, less weight. Anything else?
Plenty. It’s rigid for starters, thanks to new strut braces in the engine bay. The suspension has been tuned to take account of the extra power and lower weight with revised wheel camber settings, dampers, springs and anti-roll bars. The ride-height is 8mm lower than that of the M4 Competition and adaptive suspension with electronically-controlled dampers, variable ratio steering and carbon-ceramic brakes are standard.
The traction control system is tuneable for track use and allows the driver to set their own limits for wheel slip, with settings one to five allowing for controlled drifts and settings six to 10 intended to maximise traction and stability. The wheels, shod in high-performance tyres, are 19-inch at the front and 20-inch at the rear.
What's the result?
The M4 CSL develops 550hp, 650Nm of torque between 2,750 and 5,950rpm and can manage the 0-62mph dash in 3.7 seconds. In more practical terms, the changes mean that the CSL has posted a lap time of 07:15:66 at the Nürburgring Nordschleife circuit in Germany over the 12.8-mile section usually used for testing and comparisons. Over the full 12.94 miles, the CSL recorded a time of 07:20:20, and these are the fastest times recorded so far for a BMW production car.
It’s probably a bit spartan inside then?
Yes and no. The carbon bucket seats can be moved back and forth manually, though the back-rests are fixed and, if you want to adjust the height, it’s a job for sockets and spanners rather than the push of a button. The head restraints on the seats are removable and behind, and with the rear seats gone, there’s space for storing two helmets. Despite all this though, the CSL still gets a 12.3-inch digital instrument cluster and 10.25-inch control and infotainment display with navigation and smartphone integration as standard, so it’s not totally devoid of mod-cons.
I’d quite like one.
Understandable. The CSL goes into production in July and orders are already being taken, but be quick – BMW is only building 1,000 of them.
David Mullen - 23 May 2022
