Certainly quite interesting, although I feel his conclusions were a bit black and white. But i guess they could be regarded as true if you had otherwise equal cars.....
With regard to the anime though, I am not sure, but qould guess that since it is possible to drive 4WD cars very quickly with a similar style (inertia-drift-led) to Takumi's, that Bunta is trying to point this out, and let Takumi know that the 86 isnt actually the best car in the world. The greater traction and grip, combined with a natural tendency toward a speedier drift line that 4WD gives would be a boon to Takumi, once he masters it.
I dont think that it being Bunta's car will make a difference, the 86 was his originally, and it didnt stop him lending it out. Then again, the Scooby will be qorth a bit more....