Tharg, in theory if you were on a race track driving flat out, the answer must be yes. But even race cars regenerate battery power on braking. On the road, max power is only used intermittently. (60hp is more than enough for most cars cruising at the legal limit). Whenever the car decelerated or brakes, enough energy goes back to the battery to ensure the electric motor can provide boost power when it’s needed.
At least that’s how it seems to me. I can’t see a situation where a car on UK roads could be driven so hard to affect this, maybe on an Autobahn.