Vehicle Speed?

Quick Overview. I am trying to make a vehicle game that increases speed of vehicle every 10 spawns of a new road.
I want to disable inputs from player that effect forward and braking. I also want to set an initial speed of vehicle. I also want to change the speed when vehicle has collision with a pickup item eg speed boost, reduce speed pickup etc.

All my issues are concerned with vehicle speed.
1> I can’t figure out how to set initial speed of vehicle?
2> I can’t figure out how to change speed of vehicle based on event eg. 10 new spawns then ?? or hit pickup ??

Thank you in advance.