This is the spiritual successor to 3.0CSL, M3 CSL (E46), M3 GTS (E92) and the last generation M4 GTS. It is the most hardcore version of the M3/M4 twins, with more focus on track performance and Nurburgring lap time, which it managed in 7:15.7 over the old, 20.6km course. As usual, CSL stands for Competition, Sport and Lightweight. Although tipping the DIN scale at 1625kg sounds hardly a lightweight special compared with the 1165kg 3.0CSL or the 1385kg M3 CSL, it still represents a 100kg reduction over the admittedly overweight, standard M4 Competition, let alone the all-wheel-drive M4 Competition xDrive.



The list of weight saving measures is quite comprehensive. Firstly, the cabin is stripped of sound insulation (15kg) and rear seat (21kg) - the latter is replaced by a parcel net. The carbon-fiber front bucket seats save another 24kg. These easy modifications already contributed to more than half the weight savings. Then, the chassis cuts another 21kg by using standard ceramic brakes, lightweight alloy wheels, springs and struts. Titanium exhaust cuts 4kg. Carbon-fiber bonnet and boot lid (in addition to the existing CFRP roof) slashes 11kg, while revisions to small details like the double-kidney grille, rear lights, floor mats and air-con shave off another 4kg.



Meanwhile, BMW managed to squeeze more power out of the twin-turbo straight-six without altering its internals. By twitching the ECU alone, turbo boost is lifted from 1.7 to 2.1 bar, lifting horsepower from 510 to 550, while the 479 lbft of peak torque remains unchanged, as is its availability from 2750 rpm. Power is still fed to the ZF 8-speed automatic transmission.

Losing xDrive means the rear-drive CSL won't be the quickest M4 in terms of 0-60 mph sprint, but still it does that in 3.6 seconds, while 0-124 mph is done in 10.7 seconds. Top speed is lifted from 180 to 190 mph, still electronically restricted.



The front chassis is reinforced by an aluminum frame bolted across the suspension towers and the front end. The suspension gets specific camber, spring and damper setting, while ride height is dropped by 8mm. Wheels and tire sizes remain the same, but the rubber gets bespoke compound to enhance track performance.

Outside, the CSL can be spotted from a different kidney grille that does without horizontal elements, more aggressive front splitters with end plates and a more pronounced boot lid spoiler that cuts lift.

Priced at £129,000, the M4 CSL is as expensive as Porsche 911 GT3, which offers higher power-to-weight ratio, faster Nurburgring lap time and likely more thrills as well. However, this might be justified by the fact that its production is limited to 1000 units.