That's true Pat, but how would you show the old mileage on the OEM speedo if it died? That's why I replaced mine, however if you are the seller and a buyer comes to look at it, you get a good feel for that person by the surroundings he keeps, there are some very dishonest people out there though. I've had people buy my vehicles in the past without even driving them, even the Viper I just sold, he wanted to take it for a ride and I told him a joy ride will cost him $1000, non refundable if you don't buy it, but I will apply it to the purchase price. Money in the bank and title transferred even before he got behind the wheel with the key.
Way too many of these cars have been wrecked on a test drive.