I tried a lot of different cars and while many of them
can win, the one that I found that was the easiest to win
all of the tracks with was the krenkme/Clueless Tunes Escudo.
https://www.gtplanet.net/forum/showthread.php?p=8199250#post8199250
It does take a little bit of an adjustment period, but so did all of the cars that I tried (roughly 12 different cars). Once you get the hang of this car, you can push it hard.
It may not seem like there's enough top end speed for Le Mans/Sarthe. You will hit the limit on the straights very quickly, but the car makes up for it so much in the corners that it won't matter. I passed the rabbit right after the fifth lap started and I was not even driving my best.
The rest of the tracks are pretty easy with it. I was able to pass the rabbit on Spa by the start of the 4th lap and if I remember correctly I was in the lead on the third lap on the rest of tracks.
He did a nice job of tuning this beast of a car and you can really drive it hard, once you get used to how it handles. I highly recommend it.