That's silly .Don't you think if Tesla can actually get 2.6 seconds 0-60, they'd advertise that instead of 2.8 seconds? That would increase sales. That would benefit Tesla. There is 0 benefit to Tesla do downplay its 0-60 times.
Whereas, there is a lot of benefit to Volkswagen to reduce it's emissions (and lie), because they can sell more cars that way.
The reason Tesla may not advertise 2.6 seconds is that this can only be achieved under certain conditions (Road and Track test) and if some random guy goes to the track and only gets 2.8 seconds then he will be all over this forum complaining that "Tesla lies".
Best for Tesla to be conservative.
I have not read all of the threads of "discrepancies" in HP and time trials but I've read enough to understand that these numbers are not absolute but depend on a lot of variables (tires, altitude, temperature, track condition/dyno setup, driver, software version, etc.). Some people have taken this variation to mean that "Tesla lies". I take this variation to be just that, variation in measuring something that has a lot of uncontrolled/uncontrollable variables.
I understand that there is not one absolute answer to HP and time performance. My 85D was sold with an advertised 0-60 of 5.2 seconds and 391 HP. A few weeks after delivery a software update revised this to an advertised 0-60 of 4.4 and 420 HP. I have seen random guys post their track times of 0-60 of sub 4 seconds for this car.
I've never considered taking the car to a dyno or track to test it. I understand that there is no absolute hard and fast measurement of HP and time performance. I can live with that and, in fact, I don't worry about it at all.
The car is incredibly fast. I am happy.