My wife's car (make/model will not be disclosed) can just have the
onboard computer swapped and the mileage changes with the computer.
The dealership, or maybe it's a function of GM when they order the
part, can reset the mileage to anything. Digital odometers cannot be
100% trusted. But, to be fair, neither can analog odometers. Do your
research on a vehicle before purchasing if the mileage is a big factor.