California State Parks published the following "Transportation Tips for Groups."

According to Park Leadership, this is not policy, nor is it required, "it's only recommended." These "Tips" are not posted on the Official MDSP web site. You have to contact the Park Interpreter, Sharon Peterson (925) 837-6819,

MDSP Web Site recommends "Pilot Car"

This is the only Sign Posted near Mount Diablo State Park 
(Diablo Scenic Blvd, before the Athenian School)