[dcb]

I believe a good (and patient) driver can outperform the hybrid systems, just by anticipating obstructions and not putting him/her self in a position requiring much braking, and accelerating efficiently.

But a big part of the xprize is businessy stuff so the electronics allow you to compensate for a "bad" (typical) driver and leave the engine off and recover some braking power and play well with others in certain traffic conditions, at the cost of conversion losses and weight (and cost and complexity).