Tesla owner Emmanuel Chang had his 2013 Black Tesla Model S P85 dyno tested on a mobile Dynojet recently at some generic car show.
The Model S P85 is officially rated 416 HP (305 Kw) at the motor shaft. This particular combination of dyno and P85 recorded 436 HP (320 Kw) at the wheels. (there is usually a significant drivetrain loss between motor output shaft and wheels)
A few details regarding this test:
1) The tech couldn't attach a sensor to the motor's crank so "engine rpm" has to be recalculated as he took the wheel RPM (so multiply the RPM by 1000, then by 9.71 *approx*) 2) The dyno maxed out at 2000 lbs·ft (2710 Nm) but math from the specs indicates 4301 lbs·ft (5831 Nm) at the wheels. (The P85 outputs 600 Nm peak torque via a 9.73:1 final drive ratio) 3) Horsepower and torque number are inaccurate as the car smoked the tires on the dyno's drum so the wheels were not spinning 1:1 for the computer to measure accurately, basically it has slightly more power than what the computer thinks it has. Source: TMC