IMDB entry
http://uk.imdb.com/title/tt0303461/
Photos sent by email.
Alvis Stalwart (episode 1.01 "Serenity Part 1")
Unknown quadbike (episode 1.02 "Serenity Part 2")
Referred to by characters as the "Mule"
Unknown all-terrain vehicle (episode 1.02 "Serenity Part 2")
Unknown bus (episode 1.04 "Shindig")
See also
Buses on Screen, SteveA's site, which has screenshots by me