We all love carbon fibre. Not only does it make a car look ominous, imposing, and totally badass, but the weight savings are a huge plus. It’s why we love that cars like the Alfa Romeo Giulia feature CFRP (Carbon Fibre Reinforced Plastic) driveshafts right from the base spec models to the range topping Quadrifoglio. But now, the BMW M3 and M4 twins will be ditching the CFRP driveshaft in favour of an old fashioned steel driveshaft.
From November 2017, the CFRP driveshaft in the M3, M4, and M4 convertible will be replaced by an ‘M-specific high performance’ steel driveshaft. Why? Well, the ever-stricter emissions regulations are to blame.
BMW states that with stricter emissions regulations, they will need to start installing a Petrol Particulate Filter (PPF) into their models. Unfortunately, although the CFRP driveshaft in the M3 and M4 is lighter, therefore reducing rotational inertia and improving response, it does occupy more space than a steel unit would. BMW claim that the steel driveshaft will occupy less space than the CFRP driveshaft, creating enough space to install the PPF within the existing architecture.
BMW claim that the new steel driveshaft has been specially designed to “ensure the superlative performance and handling qualities of the BMW M3/M4 high-performance sports cars remains unaffected.”
The change is likely to go largely un-noticed, but the change leaves the Alfa Romeo Giulia now the only vehicle in segment utilising a carbon fibre driveshaft. For that, the Alfa remains just a little bit cooler – though time will tell if the Italian brand is forced to go a similar route.