the DIC brain tracks mileage, in adition to the speedometer cluster. if you dont care that they match, you can just plug it in and go. if you want the mileage to be correct, you need to have the mileage programmed into the DIC. (way around this is if you could find a DIC that had a bit more miles than your car, then when your car is to that same mileage, plug it in) -- tricky to catch the exact mileage perhaps though.