Starting in November 2017 the M3 sedan and M4 coupe and convertible will no longer come equipped with a carbon fiber driveshaft.
The carbon reinforced plastic unit will be replaced with an M specific high-performance shaft made from steel instead. The reasoning behind the switch is meeting future emissions requirements in most major markets.
It may sound odd that BMW would switch from a lighter, carbon driveshaft to one made from steel in the name of fuel economy but it’s not that simple. The new steel unit will have a smaller diameter than the carbon one, freeing up valuable space for a new petrol particulate filter (PPF) which will soon be required in key jurisdictions.
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Media Relations Manager for the M brand, Benjamin Titz, told Bimmerfest “we have to create space for the PPF which will be incorporated into the existing installation space in the M3/M4 models in major markets.
“The installation space needed for the PPF requires the driveshaft to have a smaller diameter. The newly developed steel driveshaft fulfils this requirement.”
This switch does not apply to either the BMW M4 CS or GTS which will retain their CFRP shafts.
A version of this story originally appeared on Bimmerfest
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