To find out how to unlock a particular mod, select it in the Mod Shop and at the bottom of the list it will print “This item will unlock when you reach Rank 100” [for Armor Upgrade 100%].
Just took my Gauntlet to the modshop to get a full list of unlocks for performance mods for you:
- 20% — rank 10
- 40% — rank 30
- 60% — rank 60
- 80% — rank 80
- 100% — rank 100
- Street brakes — 11 races won in this class of car
- Sport brakes — 27 races…
- Race brakes — 39 races…
- Level 1 — 3 races won in this class of car
- Level 2 — 15 races…
- Level 3 — 31 races…
- Level 4 — 43 races…
- Ignition bomb — rank 25
- Remote bomb — rank 50
- Lowered suspension — rank 17
- Street suspension — rank 36
- Sport suspension — rank 56
- Street transmission — 7 races won in this class of car
- Sports transmission — 23 races…
- Race transmission — 35 races…
Turbo — 19 races won in this class of car
Bulletproof tires — rank 20
Some cars have more options available. The Gauntlet doesn't have competition suspension or competition transmission. Also, I'm not including the aesthetic mods (which can unlock according to rank, number of stunt jumps completed, etc.). Some vehicles won't have all of these options, some vehicles will have more. I think that any car which offers a particular mod (competition suspension, e.g.), has the same requirement for unlock (whether a particular rank, or a certain number of races won in that class of car).
The least customizable I've found is the FIB SUV, which only has explosives, respray (limited options), and bulletproof tires. The most customizable car, I believe, is the Sabre Turbo, which has options like stunt cage (other cars sometimes offer roll cage), and wheelie bar.
Edited by oldak, 19 October 2013 - 06:26 PM.