Have you found a solution?
I’m using hte chaos vehicle.
When my car car stops or spawn on a slpoe (with handbrak and brakes on) it keeps moving. It feels like on parking a car on a very slippy surface. But the speed of the movement is not increasing. So i think the the chaos vehicles tires arent using a correct physics material under the hood.
I tried many combinations of the settings of Friction Multipliers and Slip Modefiers on Chaos Wheels but nothing brings to stop the car from moving.
The slippy effect also came up if i place the vehicle on a slope sideways. The car is sliding sideways down.
I also changed the physics material of ground to a very high friction. this reduces the effect a little bit but not stop the car completly.