How to keep car speed on slants?

Hi!

I'm making a car game, using Kenney's cars and city roads meshes. All is working fine, except for cars on slants.

The behaviour I'm facing is "normal", when you think about physics and gravity: when my car tries to climb up a slant, it speeds down, and when my car tries to climb down a slant, it speeds up.

But I want a more cartoon/non-realistic physics, keeping car's speed when it reaches an slant.

Since I'm using WheelCollider to handle car's movement, I thought I need to increase/decrease motor torque on slants, according the direction (up or down), but can't figure out a best way to do that... It's just an ideia, that may be very very very wrong.

So, can someone help me with this problem?

Thank you all!