True, but you already have "might be" in the line, which indicates that it it might or might not be. "could be in fact one of the fastest, if not the fastest" is overkill. More words, without any increase in content or clarity. The "in fact" should be deleted as it implies certainty which you do not have.
If it's for a non-fiction essay, it might be worth finding out if it really is the fastest. http://www.thesupercars.org/fastest-...d-top-10-list/