From what I can see there is nothing wrong with the vehicle. It goes fast because the handling line tells it to. If it is to fast for you then try a different handling line. As for it being destroyed easily, it looks to me like the guard rail in the video is a little to tall for the Bugatti and it just sort of slips under it. So its not grinding against it like it should. Its just striking the poles that support the rail and coming to a sudden stop. Which usually happens when you hit immovable objects in a fast sports car.
Also a lot of models converted from Forza don't seem to have custom damage models. They just deform however they please, which means they turn into something that resembles tinfoil fairly easily. I just turn on vehicle god mode with the simple native trainer.