BMW‘s strict choice of dual-clutch transmission for non-SUV M models as opposed to regular automatic transmissions may not be a steadfast philosophy, according to one of the performance division’s top engineers.
Speaking to CarAdvice at the launch of the BMW X6 M in Texas (United States), BMW M division chassis and power train engineer, Brend Barbisch, said the future of transmission choices for its high-performance cars will not necessarily be clear cut based on its predecessors.
“What I think about the future is that we have to compare the two different systems and maybe decide for each car.” Barbisch said.
According to Barbisch, both dual-clutch and regular eight-speed automatic transmissions have their supporters internally and both are normally considered for every M model.
“[We do] what is best from the technical side of things and what is asked by the customer, we can’t say we will always do this or do that. We always make a new decision for a new car. That’s the competition between the two systems. We always decide on each car, which is the better solution for each car.”
Barbisch admitted that the eight-speed ZF transmission used in its X5 and X6 M models provides a smoother driving experience around town and at lower speeds — something that is unlikely to be transferred into the sedan and coupe M models that make use of the well-regarded seven-speed dual-clutch transmission (M DCT).
“It’s a physical limitation [with the DCT] as you have a normal clutch and it’s not as smooth as a torque converter, but the torque converter is a little bit heavier and the shift speeds are a little bit faster with the double clutch. So do you want to lose 100ms [between shifts]?”
The current DCT in the M3, M4, M5 and M6 is a constantly updated joint design by BMW and German transmission specialist Getrag (which also makes the dual-clutch transmission in the Mitsubishi Evolution X). In its latest iteration the DCT can handle upwards of 700Nm of torque, substantially more than most standard dual-clutch transmissions.
The potential of a transmission change for cars such as the next-generation BMW M5 is certainly there, as the German company seeks to better position its core models to attract a wider and differentiated audience.
Should BMW M sedan and coupe models move away from dual-clutch transmissions? Is the sacrifice of smoother driving at lower speeds worth the loss of shift times?