Take one superior sports coupe, remove 440 lb of sprung weight, add a generous amount of F1-based technology, mix in wide wheels and lightweight brakes, and place on the Nuerburgring's northern circuit for a lap time of less than 8 minutes. The M3 CSL is BMW Motorsports' latest concept, showcasing intelligent weight reduction. The CSL is powered by a "high-speed" version of the M3 straight six, which incorporates 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.
Carbon fiber and carbon-fiber-reinforced plastic, the material used on F1 race cars, is prevalent throughout the car. The flaps in the front airdam, exterior mirror housing and the roof are unadorned carbon fiber, while the front airdam, doors and rear lid are body-colored carbon fiber. A solid sandwich panel takes the place of the through-loading bulkhead between the luggage and passenger compartments, and the two racing-style bucket seats, as well as the door linings, center console and instrument trim, are made of carbon-fiber-reinforced plastic.
Other lightweight materials incorporated into the design include high-strength steel panels (the body), extra-thin glass (rear window), weight-optimized foam (under the carpet), magnesium (the substrate beneath the instrument panel) and sandwich structures (the floorpan). In addition, the luggage compartment's floor panel is a honeycomb sandwich plate which is normally used in aerospace applications. Lighter doesn't necessarily mean spartan. The M3 CSL does forego side airbags, the toolbox and the rear seats--in their place are storage boxes--but the rest of the usual amenities remain intact.
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 Nuerburgring's northern circuit than its production counterpart.
Shown at the 2001 Frankfurt motor show, the CSL is officially a one-off concept model that is not for sale. However, those in the know say a proposal will be put to BMW Vorstand outlining a program to produce the car if enough interest is shown from potential customers. It is speculated that BMW would even build it on a break-even basis in order to gain experience in working with lightweight materials. We can only hope.