[HELP] controlling wheel collider via touchscreen

Hye guys,
I’m still kinda new. I managed to build a working terrain car using wheel colliders.

I just noticed that the controls are kinda hard coded though? You just write some lines like…

wheelCollider*.motorTorque = torque;*
wheelCollider*.steerAngle = steer;*
and the car magically starts to work when you press arrows for steering and throttle.
[QUESTION]
My question is how to adjust the momentary throttle and steeringangle of the wheels via script so I can control the car via touchscreen (in an android game for example)
Ty for directing me the right way.
A.

still no idea how to override the arrow controls?