User blog:ESA-Car-6O/Drivable Distance

A regular car can go a bit over 12.5 miles (20km) before you get red bars. You can verify this with a 5-lap Indianapolis Speedway Cup or NASCAR race (there are several in the game). Don't worry about winning, just run the 5 laps. dont touch anything or go below the white line. All 6 short condition bars will be green and the last tall condition bar will be green, but dimmed indicating partial consumption. There are 17 tall bars, so about 0.75 miles (1.2km) per bar.

A fully upgraded car can go a bit over 25 miles (40km) before you get red bars. Same technique as above in a 10-lap Indianapolis Speedway NASCAR race (FU RPM Fusion). All 6 short condition bars and the last tall condition bar are green. Same rate of condition decrease.

An R3 spec car can go more than twice as far. There is a 6-lap Indy Speedway Cup in the R3 Spec Mustang. After running that twice I still have one tall green bar left (car is NOT FU). So an R3 Spec car can go over 30 miles (48km) before you get red bars. That's about 1.75 miles (2.8km) per bar.

I don't have a FU R3 Spec car to test, but if the distacne doubles like the normal cars then an R3 Spec car can go 60 miles before red bars, which means you can run any one of the 10 lap races and still have plenty of green bars left to do another.