The New 2023 BMW M4 CSL

The question is, what does BMW do or stands for in today’s world? In short many – many things, please let me explain.

Bayerische Motoren Werke (BMW) has some well known innovations like mold injected carbon fiber polymer which had its first commercial use in the BMW E46, BMW M3 CSL . The CSL (Competition Sport Light weight) is only used twice in the brands history.

2023 BMW M4 CSL

The third one has been just announced which is going to be the 2023 BMW M4 CSL, production starts on 07/2022. The very first one was the 1972 homologation special BMW 3.0 CSL which later became the “batmobile”.

The New 2023 M4 CSL

The second iteration BMW M3 CSL was introduced in 2003, the BMW E46 with a carbon fiber roof in the first time in a production vehicle. The technology to produce carbon fiber of anything is not new albeit the polymer reinforced carbon fiber is a BMW invention entirely.

Regular or conventional carbon fiber has to be made from scratch of carbon fiber sheets which could be plain or pre preg. Either way it has to be placed or hand laid into a mold. After has to be soaked in epoxy resin, then this has to be repeated multiple times, until the layers reach a desired thickness within the mold.

Thereafter the entire soaked mold has to be covered in a special sheet of absorbent material, which has to soak up the excess resin to make the component lighter. Then the entire mold has to be covered in a vacuum bag and sealed entirely while there are sealed ports are attached to the bag so there is a vacuum ( negative air pressure) can be applied.

The negative pressure is a must, in order to extract any air bubbles from the carbon fiber epoxy resin.  Additionally the entire process has to be performed while the component is baked over night in a autoclave (a giant oven) which will cure the epoxy resin over time of 6hours or more.  BMW figured this process is way too expensive and time consuming, therefore they came up with a clever way to make the desired components in 20 minutes or less.

The BMW’s Way of Making Carbon Fiber Roof Takes 20 Minutes

The BMW’s way of making the carbon fiber roof has been, make 2 molds one positive and one negative mold. Layer up (5 layers for the roof in question) the carbon fiber sheets in different direction.  Press the carbon fiber sheet between the molds and then pre heat the molds and finally inject a polymer resin to solidify the the carbon fiber cloth.

The entire process takes about 20 minutes or less instead of days with conventional hand laid epoxy resin. The first carbon fiber roof was installed on the famous limited edition 2003 M3 CSL to bring down the center of gravity of the vehicle.

Which Brings Us Back To The  2023 BMW M4 CSL

This process opened a new era in fast and reasonably priced carbon fiber components. Therefore BMW could make the BMW i3 and the BMW i8 cars mostly constructed from the same material on a normal production line. Which brings us back to the  2023 BMW M4 CSL ( limited to one thousand piece World wide) which has multiple panels made from the same lightweight but strong (5 times as strong as steel) carbon fiber.  For instance, the roof the hood and the trunk all made of the same material to lower the center of gravity. This all played a role to earn the L  (Leicht in German = lightweight in English) designation by removing a hundred kilogram of weight from the vehicle.

Naturally even the standard seats are made of carbon fiber as well .

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2023 BMW M4 CSL

The new 2023 BMW M4 CSL

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