I know it may not apply to the Xfire since it really isn't a Chrysler, but on the more recent ChryCo products, the mileage shown in the cluster is based on what is stored in the ECM. I swapped clusters on a 2002 Caravan and it picked up the mileage of the vehicle and reset the cluster.

I would think the Xfire would be similar, but I have no 'real' experience with it to let you know.