Q:
A: None of the answers so far are right. I have a 206 so I know! When the actual mileage of the car is displayed (i.e. after the miles until a service has gone) press the button to the bottom right of the speedo. This will then show the trip reading... it is only when the trip reading is shown that you can reset it by holding the same button for 3 secs. Hope this helped!