The i3s's system is calibrated to help it to pull away quickly from a stop, making full use of the instantaneous torque offered by the electric motor. It also improves stability when accelerating out of corners, when using regenerative braking and, of course, when the road conditions are less than ideal. The results are palpable, and with the other improvements the i3s definitely feels stronger off the line, as we found on our drive. It's also about a half-second quicker to 60 miles per hour, at 6.8 seconds.
The secret is in the response time of the stability control, which BMW claims is 50 times faster than the conventional system. This is made possible by moving the control process into the powertrain itself, rather than a remote unit. This reduces the signal path and, thus, the response time of the traction control system. BMW's Head of Chassis Development, Peter Langen, said of it, "With their high levels of torque and instantaneous responses to every movement of the accelerator, electric motors already make significantly higher demands on driving stability systems than conventional power units."
While engineered to make the most of the electric motor, BMW says the shorter cycles of this traction control system show promise for internal combustion vehicles as well. As such, we'll begin to see the improved technology applied across the BMW and Mini lineups going forward.