The new M4 CSL is a 543-horsepower track junkie weighing in at 3,640 pounds, after losing a rather heavy passenger’s worth of weight through clever engineering and material upgrades. For those of you who care deeply about Nürburgring times, the new BMW M4 CSL’s 7:20.2 result puts it right between a Ferrari 488 GTB and a 991 Porsche 911 GT3 RS. That’s not too shabby for a front-engine coupé costing considerably less. Yet it is far more interesting how BMW managed to create its most hardcore M3/M4 special edition to date.
In the spirit of the “Competition, Sport, Lightweight" moniker, an evolution of the original 1973 BMW 3.0 CSL’s “Coupé, Sport, Lightweight” badging, the M4 CSL’s weight-to-power ratio of 6.7 pounds for every horsepower equals a 0 to 60 mph jump in 3.6 seconds, while top speed is limited to 191 mph.
Finding 240 unnecessary pounds in an already performance-oriented road car is tough. However, by making the CSL a two-seater equipped with M Carbon full bucket seats only, BMW managed to immediately cut 99 pounds. Then came the chassis alterations, including the standard M carbon-ceramic brakes (15.7-inch front and 15-inch rear), forged alloy wheels (19-inch at the front and 20-inch at the rear, finished in matte black), and lighter springs and struts teaming up for another 46 pounds off. A minimalistic approach to sound isolation meant 33 pounds, while additional CFRP components inside and out saved 24 pounds in total. The modified BMW kidney grille, along with the different rear lights, lack of floor mats and automatic climate control lost eight pounds, and the titanium rear silencer is nine pounds lighter than the M4’s standard exhaust system.
While the M4 Competition comes with a CFRP roof panel, the M4 CSL goes further with a “double bubble” CFRP roof, a carbon fiber hood (three pounds lighter than an aluminum one), as well as a CFRP trunk lid that saves a more substantial 15 pounds over the M4 Competition’s aluminum piece. The trunk lid features a ducktail spoiler, and there’s a diffuser integrated into the rear apron also made of CFRP, not unlike the CSL’s mirror caps. To show off this composite extravaganza, the CSL’s hood features two unpainted channels extending in line with the modified grille. These are even bordered in red, just to make sure you spot all the aero.
Running over the contours of its extended side sills and splitter, the red accents are designed to go perfectly with BMW’s new optional Frozen Brooklyn Grey metallic paint. However, you can also choose your M4 CSL in standard Alpine White or Black Sapphire metallic, leading to color options that include grey, white, or black. The BMW M 50 Years emblems are standard for the hood, trunk lid and wheel center caps. These recall the blue/violet/red logo first seen on BMW’s touring cars in 1973, and countless base BMWs ever since. BMW even changed its model badges for the CSL, this time using black surfaces with a red outline.
BMW Laserlight headlights are standard, and the angular daytime running lights illuminate in yellow rather than white. Meanwhile, the rear lights feature technology making its debut in a series-produced car. I’ll let BMW explain that one:
While all the light functions use LEDs, the glass covers have intricate light threads woven into them which are illuminated using laser technology, bringing a vibrant structure to the surface of the rear lights and creating a distinctive light signature recognizable from a long distance after dark. The arrangement of the three threads, which run parallel to one another across the inner section of the light units and overlap each other in the outer area, creates a visually stunning interpretation of the hallmark BMW L-shaped rear light contour. Additionally, the illuminated “BMW Laser" lettering on the light covers hints at the innovative light technology below the surface.
Woven light threads hit by lasers! Take that, Audi.
The M4 CSL uses stiffer engine and transmission mounts, as well as a double-joint spring strut front axle and five-link rear axle. It comes with adaptive M Suspension with electronically controlled dampers, variable ratio electromechanical M Servotronic steering and an M-specific version of the integrated braking system, which offers two-way adjustable pedal feel.
Model-specific camber settings thanks to the front axle's forged swivel bearing, new dampers, auxiliary springs and anti-roll bars improve cornering, while ride height compared to the M4 Competition was dropped by 0.3-inches. On the rear axle, four additional ball joints with zero play replace the rubber mounts for the control arms on both the axle subframe and wheel carrier sides, thereby lowering the secondary spring rates. The rear-axle subframe has a rigid connection to the body without any flexible rubber elements. That, you shall feel over a bump.
The M4 CSL is running on Michelin Pilot Sport Cup 2 R tires measuring 275/35 ZR19 at the front and 285/30 ZR at the rear, and its traction control system has five new settings for track usage. While stages 1 to 5 are the same as in the M4 Competition, 6 to 10 are mostly for circuit use. BMW says that the intervention thresholds are set extremely high in stages 6 and 7, which are designed for driving on a dry track with the tires at optimum temperature. If the tires are cold or too hot, however, or the track is damp or wet, drivers can engage stages 8 to 10, which gradually lower the intervention thresholds.
Engine and Transmission
It has 543 horsepower at 6,250 rpm, and peak torque of 479 lb-ft from 2,750 rpm to 5,950 rpm. To get an extra 40 horses out of the 3.0 twin-turbo six-cylinder, BMW modified the management software to raise boost pressure from 24.7 psi in the M4 Competition to 30.5 psi in the CSL. The engine mounts' spring rates - which are set at 580 N/mm on the left side and 900 N/mm on the right in the BMW M4 Competition - were both increased to 1,000 N/mm. Meanwhile, the transmission mounts are 12 percent stiffer. With the upgraded M Steptronic transmission, the CSL will accelerate to 120 mph in 10.5 seconds, and if you blip the throttle, the eight-speed ZF unit will even reduce undesirable engine braking when the car is being pushed hard.
Most crucially, the CSL’s lightweight titanium silencer is equipped with two electrically controlled flaps to give this special edition a distinctive engine note at a push of a button.
For your $141,000, the M4 CSL features a CFRP central console, as well as such comfort features as a leather-padded armrest and a wireless charging tray. The Alcantara steering wheel comes with a red center marker in the 12 o'clock position, carbon-fiber inlays on the three spokes and CFRP shift paddles. In front of those, the pair of bucket seats at your service are equally Leicht.
Created for this model, the M Carbon full buckets offer extremely high lateral support, and not much else. The backrest angle is fixed, and the seat height can only be adjusted in a workshop using a three-stage screw linkage. Fore and aft adjustments are made manually using a lever on the front edge of the seat. The head restraints can be disassembled for track use when the driver and passenger are wearing helmets. The seating surfaces and backrests are trimmed in black Merino leather, while the head restraints have red Alcantara inserts. Contrast stitching in M colors on the seat bolsters and the seat belts is a given.
If you don’t like the sound of that, heated M Carbon bucket seats with full power adjustment are available as a no-cost option. However, these seats are only 21 pounds lighter than the standard seats in the BMW M4 Competition, probably making it slower than a Ferrari 488 GTB around the Nordschleife. The stowage area behind the seats provides space for two helmets, as it should.
Happy birthday BMW M GmbH, it’s been one hell of a half century already, and the M4 CSL seems proper.
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