In IR3, the heavy roller becomes very burdened while trying to smash through trees. I've also noticed that a lot of the vehicles I'm driving easily get stuck on any entity it gets near. When I disable the mod, collision boxes are smaller and I don't get stickied onto trees/cliffs/entities.

The reason that's happening is because the mod sets vehicle speed to 0 when one of the collision points collides with something, however that system was implemented to prevent "sliding" when you drift so the car's butt is touching water or something. Now that I'm thinking about it, I can do that only when the points opposite of the direction you're driving collide, and leave it as is for the others.

I finally got around to improving the collision detection code a bit, so you should have less issues colliding with things from the front.
Added in 0.0.14

Feels very good but if you drive at high speeds and hit a tree / stone with the car tail your internal velocity is sometimes reset to 0

That is intentional, otherwise the car "bounces" off of things. I'll add damage so it doesn't feel unnatural later today.