Am I the only one who noticed in at least a couple of the recent direct-to-video Scooby-Doo movies, the gang has a slightly modernized-looking Mystery Machine? I've seen it appear in "Shaggy's Showdown" and "Gourmet Ghost." Yet other movies from the era that have the Mystery Machine show its' 1969 model (despite sounding like a van made in the 21st century), even its' brief appearance in "Curse of the 13 Ghost!" I will say this is a rather interesting update in some of the direct-to-video movies, and fits with the more modern style the movies have. It certainly looks better than the minivan Mystery Machine from the first four direct-to-video movies, IMO.
They have a fleet of Mystery Machines, they are limited in using the original one due to the milage restrictions of classic vehicle insurance, limited parts availability and that leakage from the secret food storage compartments have begun to compromise the integrity of the sub-chassis.