Last time we saw the Tesla Model S on a dyno, it turned in 388 horsepower, but the folks over AutoCar wanted to see for themselves just how much power the electric Tesla Model S can deliver.

They took the electric sedan to the folks at Surrey Rolling Road Ltd., and put the Model S->ke3329 to the horsepower test. The resulting 428.2 horsepower is rather impressive, considering Tesla only rates it at 416 horsepower. This also makes us wonder what the other testers did wrong to lead to the Model S pumping out drastically less power.

This amount of power is enough to make the new Tesla S Performance into a super-fast electric sedan that can sprint from to 60 mph in just 4.2 seconds and up to a top speed of 130 mph. All of this while putting off zero emissions -- not bad at all.

.