I called my dealer to arrange a service for my 91 Accord, which just turned 100,000. The service person says that they don't have any records for the car and explained that the system wipes records for any car that hasn't be serviced in six months.
I'm a computer programmer and nothing is cheaper than disk space these days, and I could likely fit all of the maintenance records of all the Accords in the US on one of my PCs. It just doesn't make any sense that they would wipe out stuff.
I don't do much maintenance of the car at the dealer, but the car was originally bought there by the previous owner and I have had it there several times. The original owner had all of the maintenance done there.