The M3 CSL is Beautifully Engineered
The last and best evolution of the straight-six powered M3
The BMW M3 CSL (Coupé Sport Leichtbau) was a limited edition version of the M3, with only 1,400 cars being produced for its 2004 model year run. The CSL was never released into the North American market, and was only available in two colours – Silver Grey Metallic and Black Sapphire Metallic.
As its name suggests, an emphasis was put on reducing weight. The M3 CSL has a curb weight of 1,385 kg (3,050 lb), 110 kg (240 lb) lighter than the regular M3. A large proportion of the M3’s sound insulation has been removed, electric seats, and navigation systems. Air conditioning and stereo systems could be retrofitted free of cost, but were not available standard. The CSL’s unique body pieces are all crafted from carbon fiber reinforced polymer. Glass-reinforced plastics are used throughout structural points in the car. The standard rear window was replaced with one made from thinner glass.
Although the CSL loses a considerable amount of curb weight from its original version, the focus was put on strategically reducing or moving the weight in the car rather than the raw amount of weight that could be lost. This is to retain the ideal 50:50 weight distribution characteristics the E46 has. For example, the roof is constructed from carbon fiber reinforced plastic. While this only reduces the curb weight of the car by 7 kg (15 lb), it lowers the center of gravity of the car and decreases body flex.
In order to improve the handling ability of the car, the entire suspension system was further refined. Specially developed racing springs and dampers are given to the CSL, and a tightened steering ratio (14.5:1 vs 15.4:1 on the regular M3). The braking system is also modified, with larger front and rear floating rotors and calipers from the E39 M5. The CSL is given a retuned dynamic stability control system with a “M track mode” setting that allows the car to be pushed to its absolute limits before being activated.
The 3.2 L engine used in the M3, the BMW S54, has been modified to increased output by 17 hp (13 kW) and 5 N·m (1 lbf) over the European M3. This is achieved through a high flow carbon fiber air intake, modified valve and camshaft timing, and a retuned DME. However, the engine is further modified in order to reduce weight – it features a lightweight exhaust manifold and thinner exhaust piping. Additionally, the intake and exhaust manifolds are slightly straightened to improve engine responsiveness.
Unlike the standard M3, which was offered with a standard 6-speed Getrag transmission, or optionally a SMG drivelogic transmission (also known as the SMG II), the CSL was offered only with the SMG II transmission. This is the standard 6-speed Getrag transmission with an electrohydraulically actuated clutch pedal, similar to a Formula One style transmission. However, the CSL received a more advanced drivelogic unit than the standard M3 that was capable of making shifts in 0.08 of a second.
The CSL also has various aesthetic modifications over the standard M3. It received an aerodynamic lightweight body kit which included carbon fiber front splitters that improved downforce at high speeds by 50%, as well as a carbon fiber rear diffuser. The front bumper has a distinct hole that is used to draw cool air into the newly designed air intake. The trunk floor is made of lightweight fiberboard. The trunk lid is redesigned to incorporate a raised lip, unlike the standard M3 where one is simply added onto a flat trunk. The CSL was sold with distinct 19-inch lightweight cast BBS alloy rims that came with Michelin Pilot Sport Cup semi-slick racing tires.