M3 CSL

You start with the fastest M3 in the world, the V-8 powered ALMS M3 GTR racer, reduce the weight even further with lightweight materials, and then make it street-ready. That's what the M3 CSL is all about.

Take the E46 M3, reduce sprung weight, add a generous amount of F1-based technology, mix in wide wheels and lightweight brakes, and place it on the Nürburgring's northern circuit for a lap time of less than 8 minutes. The M3 CSL is BMW Motorsports' latest, showcasing M Power and intelligent weight reduction.

Unlike the M3 GTR racecar, the CSL is powered by a version of the M3 straight six. The engine utilizes a streamlined cylinder-charge process and a reduction in cylinder friction, boosting output to more than 350 bhp. BMW's Sequential M Gearbox with Drivelogic, featuring microprocessor-controlled clutch operation, allows for extra-quick shifts via two steering-wheel mounted paddles and ensures a direct power flow at all times. Supreme stopping power is provided by 18-in. lightweight brakes that are visible through the spokes of the wide, 19-in. wheels.

Reducing the weight of the M3 was not BMW's end goal in itself. Instead, the CSL was engineered with the consideration of absolute weight and the mass inertia of the car around its vertical axis--crucial areas to the vehicle's lateral, vertical and longitudinal dynamics. The result is a significant improvement in the power-to-weight ratio: 7.7 lb/bhp versus 9.6 lb/bhp for the production-series M3. A better power-to-weight ratio translates to faster acceleration.

The CSL was nearly 30 seconds faster on the Nürburgring's northern circuit than its production counterpart. 0-60 mph should take 4.6 seconds and 0-100 mph in less than 11 seconds. The handling has been revised and steering has a more responsive feel. The M3 CSL comes on specially developed 19-inch wheels with new sports tires again reflecting the purist concept of the car, while the 18-inch brake system ensures supreme stopping power.

The price of the M3 CSL will be about $250,000, with final pricing to be released later. The M3 CSL will be offered only with Steel Grey or Black Sapphire paint trim.

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Lightweight Technology

This strategy leads straight to Formula 1 technology featured by the M3 CSL in some fundamental areas for practical use on the road. One example is the consistent utilization of carbon-fiber reinforced plastic (CFRP), the material in Formula 1. Now introducing this material on the road, BMW M is turning around the weight spiral in a new, fascinating process of evolution.

In terms of drive technology this is accompanied by the high-speed concept of the famous M3 straight-six power unit reducing weight to a minimum in the engine sector. On the modified engine the complete cylinder charge cycle has been modified and frictional forces further reduced. The Sequential M Gearbox with Drivelogic (SMG)--also based directly on Formula 1 technology and forming an integral part of the most sporting M3--ensures an ultra-fast gearshift with a seamless, direct flow of power.

Lightweight technology was however not a purpose in itself in the development of the M3 CSL by BMW M. Rather, the absolute weight and mass inertia of a car around its vertical axis are crucial to the car's lateral, vertical and longitudinal dynamics - that is the way the driver experiences the car's dynamic performance on the road. The car's power-to-weight ratio--the quotient of vehicle weight versus performance--is furthermore crucial to supreme longitudinal dynamics, that is, very fast acceleration.

The best place to test all these dynamic criteria quickly and thoroughly is the Northern Circuit of Nürburgring, the most challenging race track in the world. This is where the best stand out from the rest in terms of driving dynamics, where you experience the interaction of all of a car's components.

Just one look at the BMW M3 CSL reveals the outstanding role of this lightweight concept: The flaps in the front skirt, roof and rear diffuser are visibly made of CFRP. Indeed, the entire front skirt as a whole is made of painted carbon-fiber, as are the door- and side-sills as well as the center console.

But it is not always carbon-fiber alone. The load-bearing structure supporting the asymmetrically split through-loading system, for example, is made of endless glass-fiber thermoplastics, an innovative material carried over from aerospace applications. The bucket seats at the front, imade of glass-fiber reinforced plastic (GFRP), are not only lighter than the standard seats in the M3, but also offer the occupants even greater support when driving fast and dynamically. The rear window of the M3 CSL is made of thin glass, the floor beneath the luggage compartment is a honeycomb sandwich plate, again a material used preferably in aerospace applications. Even the base material beneath the floor carpeting is made of weight-optimized foam.