There are many different cars used in leagues so there's no point in concentrating on 1 car. Though that depends on what league you want to participate of course. I would suggest you try the GTi on a few different tracks just for a bit sightseeing just to get a bit familiar with them. All the rest is up to you and what you like, some new people like to drive the BF1 as their first "new" car but be aware : the transition between slick/aero cars and the "road" cars can be quite difficult when you're new to them. If I had to do it all over again, I would start with the GT (xr gt) and then the GTT (xrt) etc. etc. (always just one class above them) instead of just picking the fastest car.
Tough race, lotsa walls
Our speed wasn't anything to write home about but somehow we ended with a rather nice endresult. Good race, and good driving from all the participants too