Car Timer

Question

Trying to find away to get my car image to slow down from an initial fast speed before stopping using this timer. Can someone offer some help please I don't no how to link my image to these calculations 


private int speedCounter = 100; //Speed for this many intervals
  private void timer1_Tick(object sender, EventArgs e)
  {
 

           if (speedCounter > 0)
                {
                  --speedCounter;
           if (timer1.Interval < 600)
                {
                  timer1.Interval++;
                }
         else
               timer1.Enabled = false;
                }
   }