First drive: the BMW i8
BMW's future-proof hybrid sports car is finally here, and we've driven it. But what's it actually like?
Posted: 03 Dec 2014
Er, calibration? Explanation please.
The engineers say the hardest job on the i8 wasn't the new materials or the weight or body. It wasn't even the power units per se. It was getting them to work together, getting everything smooth and maintaining the right variable torque split in corners. Imagine, you change throttle position. The petrol engine reacts, but with a bit of a delay as turbos do. So the electric front motor, and the auxiliary rear motor, have to be controlled to match that transient state, while maintaining the target front-rear torque split to keep the cornering dynamics right. Whatever of the six gears the petrol engine is in. However much grip each wheel has. Mind boggling.
Best not to think too hard. Just to let it get on with it, and enjoy the results, which except in that one tight-bend understeer situation, are fine. Anyway, the engineers say they're still working on a stickier front tyre compound, which should help too.