Asked in our Discord and got this reply from Catador:
[6:19 PM] Yazzo: http://fzerocentral.org/viewtopic.php?t=14177 - anyone with knowledge on this?
[7:32 PM] Catador: Yellow/orange/brown (whatever you call them) cars aren't affected
[7:32 PM] Catador: what is affected is the rate in which stationary explosive cars appear
[7:32 PM] Catador: let me pull up my data
[7:39 PM] Catador: What changes depending on difficulty:
Note: Master is the same as Expert, the only difference is the AI cars maximum top speed, which goes from slightly below 478km/h to a full 478km/h
AI cars top speeds
AI cars turn speed
Minimum distance that an AI car can be from the player before the game teleports it right behind the player
The minimum amount of brown cars that can spawn before an explosive car spawns(edited)
[7:40 PM] Catador: For the explosive cars, you can refer to this:
[7:42 PM] Catador: https://pastebin.com/raw/h2eJfwxK
Minimum amount of brown cars that can spawn before an explosive car spawns, values in hexadecimal(edited)
[7:42 PM] Catador: The game will always spawn 3 explosive cars, then 1 stationary(edited)
[7:44 PM] Catador: Notice Red Canyon II's value of 00
[7:45 PM] Catador: it's the only track where you can see 2 explosive cars together(edited)
[7:47 PM] Catador: I wonder how unfair the game would be if I were to set all of these to 00