Efficiency - improving measures include optimised underbody air ducting, wheel bearings with a lower
friction coefficient and
tyres with reduced rolling resistance.
The traction assistance provided by the double - disc clutch is especially noticeable when the
friction ratio between the
tyres and the road is low, since the clutch locks the powertrain mechanically during moderate starting if the
friction coefficient between the
tyres and the road is less than µ = 0.3 (more or less equivalent to snow).