Figured I'd share my experience with the mod.

I had a save that went a couple of in-game months. I wasn't exactly aiming to farm this skill, but I did run down quite a few zombies in various vehicles and had a couple of hoods badly banged up. Really the only other mod that should have done anything with vehicles at all was Filibuster Rhymes, and I'd adjusted the sandbox settings to have cars take more damage on the premise this would offset that to be 'slightly harder'.

The character currently has 24 exp in Controlled Impact.

I then decided to do a test with just debug, this mod, and a fresh Apocalypse start and after going full GTA down the highway until the windshield smashed that character got to 7 exp - the hood was gone and the engine was at like 80% condition.

That does seem to kinda be in the correct ballpark - if I'm understanding correctly then at level 0 you only get XP 20% of the time, and it's points equal to 20% of the damage taken, then that's 300 damage you need to take just from the wrecks that give exp, nevermind all the unmitigated damage!

It does seem like leveling the skill is totally impractical for a character that doesn't start with it, which is unusual, but even then it's basically a free 'saving throw' against car damage for any character.

This does somewhat sum up the design issues I had when making this mod. Halfway through I started questioning a lot. What does this add? Does it make sense? How is it reasonable? There isn't really a skill that rewards doing something wrong, like this mod. You gain XP by wrecking, which is the opposite of what one is supposed to do.

Like increasing the XP gains makes sense, but then wouldn't that make it much easier to make cars too durable? And then once again isn't that the point of this mod?

Increasing the probability at lower levels is something else, but that goes against how low levels are supposed to be low.

I'm open to suggestions, as I have no real idea where to go with this besides sticking a x5 multiplier on the end of XP gains as yes. It is stupidly slow.

A pint of sweat saves gallon of blood.
I find this mod to totally have it place. It allows player to wreck cars he does not want to then being able to drive around with his preferred vehicles, suffering lesser penalties from impacts.
It would be better it it would work in reverse, by awarding exp when driving past zeds at certain distance(lets say 2 to 5 tiles), without hitting them, but this works as well.

That's actually a novel idea. I dunno how capable I am at making such detection with low impact, but I really actually like that idea.

Explain how this mod works and what it does in-game.
Imagine this mod was snuck inside the game....(or was as part of 150 mod list which I forgot all the mods I added to)
How would a player find out about it or how it works?

I only explained this in the description...