How does Ford know how many miles are on my dad's new truck? They mail letters saying the truck has so many miles and it would be wise to add an extended warranty soon. The mileage readings in the letter are real since they are very close to actual odometer readings. I am beginning to wonder if the vehicle isn't somehow transmitting information regarding odometer readings among other things. Does anyone know more about this? What modules are part of this? How does it communicate? Thanks in advance.