what was the name of the movie where the man guy washed his car that the cops wanted before he lit it on fire becose the police were looking for it

It sounds most likely like The In-Laws (1979) , which has a scene where a car gets driven through a paint booth/car-wash-style setup while the authorities are chasing it, and it ends up with flames on the car.

A couple of other movies people often mix this up with are Gone in 60 Seconds and Shooter , since they also have car-changing or escape scenes involving police pressure.

If you want, I can narrow it down further by the car color, actor, or whether it was a comedy or action movie.