Lightweight Design across the board: Shedding weight in all the right places.
Intelligent lightweight design was a top priority in the development of the BMW M3 and BMW M4. The goal was to minimise kerb weight in order to give both models outstanding driving dynamics and exemplary efficiency. These measures have delivered impressive results, giving the BMW M4 Coupe a kerb weight of 1,497 kilograms, around 80 kilograms lighter than a comparably equipped predecessor model – with benefits for driving dynamics and fuel consumption as well.
BMW M3 Sedan also gets CFRP roof for the first time.
On the outgoing models, the CFRP roof was confined to the Coupe version. Now, for the first time, the four-door BMW M3 will get this striking design and functional feature as well. The CFRP roof brings weight savings of five kilograms in the case of the BMW M3 Sedan and more than six kilograms in the case of the BMW M4 Coupe. It also lowers the vehicle’s centre of gravity, which has a positive impact on driving dynamics.
Made from aluminium rather than conventional steel, the front side walls and the bonnet (with power dome) make an important contribution to the models’ lightweight design concept, while at the same time improving axle load distribution.
On the BMW M4 Coupe, the contoured roofline with central channel continues into the boot lid, emphasising the even sportier personality of the new model. The newly developed boot lid not only provides extremely effective tail end styling, its geometry is at the same time precisely tailored for optimised aerodynamics, while the use of carbon fibre and plastics makes for additional weight savings.
The new BMW M3 Sedan and new BMW M4 Coupe also feature a CFRP propeller shaft. The high rigidity and low weight of the CFRP tube mean that the propeller shaft can be produced as a single-piece component, without a centre bearing. This achieves weight savings of 40 per cent over the previous model and a reduction in rotating masses, which in turn results in more dynamic powertrain response.
The CFRP precision strut in the engine compartment is a further example of how all weight-saving measures on these vehicles have also been tailored to the improvement of driving dynamics. Weighing only 1.5 kilograms, the strut brace offers superior rigidity to a comparable aluminium component, and at the same time plays a key part in the excellent steering response and precision of both vehicles.
The use of carbon in these models is a reminder that BMW is a global leader in high-strength, lightweight CFRP construction, and that it was BMW who brought out the first mass-production vehicle with a body consisting entirely of this material – the innovative BMW i3.