I have all the cars in the game and I dont have enough time to drive them all. But just on Thursday I decided to sort by mileage and I am taking every car at the lowest spot and entering it in a few tournaments etc until they have about 50 miles. Then when I get back to them I will drive them for another 50 miles etc.
So right now my total mileage is 45,000 and my lowest car is the Mitsubishi Lancer Evo VI Tomi Makinen Edition (non-stripe). Mine is black with gold BBS rims. It has 12.7 miles and I am doing Japan Champs Amateur and as many other tourneys as I want to including GT World Beginner.
My highest mileage is Escudo with 2,470 and that is because I always do the rubber band trick on Super Speedway endurance. Next to that is F094/S with 1,117 because I have now done Formula GT twice. Then after that is SVT Mustang at 1,095 because I used it to do super speedway like 6 times to win an F1 and it was also one of my first really powerful cars. After that is Miata (950miles) Skyline GT-R R34 (706) and then is starts dropping off pretty fast.