With Panther, some customers use Household miles, some use PC Miler. What we get paid for is the number of miles on the QC load offer.
I have been shorted just about the same number of miles that I have been overpaid for. I'll have one load that drives 40 miles longer than the offer, then the next load may drive 20 miles shorter, and then the next on after that may be 20 miles shorter. Usually, mine are somewhere within 15 miles up or down.
When I accept an offer and then plug it into the Garmin, if it's significantly off from the QC I'll run it for Car, then Truck, and will run it for shorter distance and faster time for both vehicle types. Then I'll run it through the laptop and play with a few things, too.
Sometimes the vehicle type as car is the same miles, and Truck is what's 30-50 miles further. And sometimes I'll look at the route and decide that I'd rather eat the miles and run the Truck route because I'll keep my sanity longer if I do.
If it's within 10% either way I don't bother with saying anything. If it's significant, I'll ask, and usually find out that it's Rand McNally or Household miles.
I've backed out out of a load only once because of the lowball miles, and that was because the dispatcher was a tool about it.
But generally speaking, the over and under washes out to be about the same.
Slow and steady, even in expediting, wins the race - Aesop