How do I colour an asset in Blender 2.82?

  1. What do you want to achieve?
    I want to colour a car @FrozenZibra kindly made me in Blender.

  2. What is the issue?
    I am unable to colour it correctly; when using shading, the entire car changes colour.
    image

  3. What solutions have you tried so far?
    I attempted to use vertex paint and texture paint however vertex paint coloured the entire thing and texture paint was hard to use as where the paint was going was really off.

All help is appreciated, I’m pretty new to Blender. Is there any way I could do this? Thanks!

I fixed it by making the car blue, dirtying the vertex paint and painting the headlights! The result was great!