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