You'll need to win the final race least is most.
You will want the Ferrari or Aventador, maxed out. This race is mainly long straights so these have the best top speeds. I also found sliding the nitro to power really helped.
The main problem with this race is your team mates. They will nudge you into obstacles, block your path and be a nuisance. The normal traffic is bad too.
Go to settings, then game settings and choose play alone. This gets rid of other players and lowers the collision rate. This is a massive help in clearing the roads as much as possible
I completed this race with 5 seconds to spare. The key is to utilise your Nitro on those long straights and to boost around corners.
Try to keep your movements as smooth as possible to keep speed up. This race is much easier then all the other final races but your tuning, upgrades and ability to weave around traffic will make or break this