What the creators did not need, was using a fake motorcycle instead of real one. Yes, they have done this earlier (Dhoom 1’s Hayabusa to Pulsar, Race 2’s Lamborghini to cardboard car, etc), but this is 2013 and we are talking about Dhoom 3, which is expected to be the most action packed movie this year. How could they have allowed such a silly error.
And sadly, this was shown by them in the very first official trailer. The scene is such that at one moment Uday is filmed riding a BMW S1000RR with Abhishek as pillion, and a few seconds later, the bike is converted to a modified Yamaha R15, which seems to be a Bajaj Pulsar (notice kick-start!). It is still not certain what bike it is, our best guess is, that it is a Bajaj Pulsar, with modified front fairing as that of Yamaha R15. You can watch the trailer for yourself below, the scene at 1:22 shows BMW superbike and the scene at 1:56 shows a Yamaha R15. Another one is why are they not wearing helmet?
Anyways, these two bikes were recently spotted at a garage by Team-BHP, giving us a closer look at the fake BMW superbike used in the film. The original superbike is standing right next to the fake one. Considering that this is an extensive job done, you can expect to see more of Pulsar based R15 in the movie, especially where action scenes are concerned.