Detect if UI Button is pressed

Hello, So I have a script taht whenever I press the Space key I can drive a car. This works fine, but I'd like to have it so that only when you press a GUI Button the car drives. Here's the current script: using System.Collections; using System.Collections.Generic; using UnityEngine;

 public class CarControl : MonoBehaviour {
     WheelJoint2D wj;
     JointMotor2D mo;
     void Start() {
     wj = gameObject.GetComponents<WheelJoint2D>()[0];
     mo = new JointMotor2D();
     }
 
     void Update() {
         if (Input.GetKeyDown(KeyCode.Space)) {
     mo.motorSpeed = -1000;
     mo.maxMotorTorque = 1000;
     wj.useMotor=true;
     wj.motor = mo;
 }
         if (Input.GetKeyUp(KeyCode.Space)) {
     wj.useMotor = false;
 
        }
     }
 }
 

Thanks!