The Tesla S is NOT faster than an M5. It may have a slight advantage off the line, but that is about it.
The test that everyone talks about is bogus in my eyes. The Tesla driver jumped the start pretty noticeably, and the M5 driver launched like there was a cop next to him (okay I exaggerate a bit here, but the launch was clearly not a best effort). Also, if you really pay attention, the M5 driver granny shifted as well. IMO, they used a manual M5 because there is no way to sandbag a run in a DCT M5 without clearly letting off the throttle.
They also conveniently used an engineered test finish speed of 100mph, because there would be no way they could find a way to show the Tesla winning in a traditional quater mile. The M5 would just suck the doors of the Tesla in such a contest, and there would be no way to hide that.
These are obviously my opinions, but c'mon, the M5s are capable of 11 second quarter miles at over 120 mph, and the Tesla is nowhere near that universe.
Like I said, it was an engineered test, using all Tesla-vested-interest participants, with all parameters constrained to the Tesla's advantage.
If I owned the M5, there would be zero chance that Tesla would win, even if race was constrained to 100mph. I would be in it to win in my M5 (dct, of course), and that Tesla would be sucking on the fumes from my climate-altering, Polar-bear downing M5.
I could run that same test and convince most viewers that a stock VW GTI is faster than an M3, but those with a brain would see right through it (provided they were not blinded by subconscious political ideology like many are for an electric car).
Witch all that said. I feel the Tesla S is the best of breed for current electric cars, and is one of the best looking sedans I've laid eyes on.