Hi, first i would like to apologize if this is placed in the wrong place.
Ok, so ive been having a hard time racing Sport GT cars on unbeatable. Im looking for the best cars for the class. Ive played with a bunch and am having a rough time placing anything besides mid range. Any cars/tune tips would be muchly appreciated. Thanks for reading and your time 
Probably easiest to just look at the Free Play leaderboards for whichever track(s) you’ll be running. There’ll usually be a few cars that are consistently at the top. Any of them should work. Just pick the one you like the best for whatever reason.
Also keep in mind that the AI outright cheats on Unbeatable difficulty. They get a bonus to power and grip that can, depending on the track and cars, make them faster than the fastest aliens on the leaderboards. Basically any track where top speed is important they’ll have a huge advantage over you.