[BRTHTAKR]

It's not so much how much torque, as how fast it comes on. As a Dentist, I can tell you that an electric motor achieves (and maintains) full torque almost instantly. It's either on or it's not.
Coming out of corners this would have to contribute significantly to time.
The Tesla in the Topgear episode (and it's always in top gear, single speed) had tires designed for low rolling resistance, not grip. The recharge times on Topgear were for a lower voltage recharge I think.
This is all early development. It is just a matter of time until electrics show up on track and change things for good. Lighter batteries with more range, faster recharges, reliable transmissions and we're in a new league.
The Japanese have made a car with separate motors for each wheel that is astonishingly fast. Can't remember the name.