How would you make a car such as a-chassis automatically accelerate?

The title says it all, I’m trying to make an a-chassis car automatically accelerate without pressing any keys. You can still control the steering and everything else but the acceleration. Another example would be when you sit on the vehicle seat the chassis automatically starts to throttle the moment you sit down.
Any help would be greatly appreciated, thanks.

Have you tried writing a script that is triggered by the player sitting and just increments the speed over time?

Thanks for the feedback, I’ll test that method.

Also if you want to do it (your choice) could you provide a simple example of what your trying to implement?