|The following is based on Van Buren and has not been confirmed by canon sources.|
Semi-trailer truck (simply called truck in game) is a drivable vehicle available in the Midwest.
A road tractor is a high-powered truck designed to pull trailers; the mobile science lab can be attached to it. It was originally designed to be a vehicle with an infinite storage capacity that could also transport other vehicles.
- J.E. Sawyer: "It changed after I left Black Isle. In my write-up, the semi carried practically infinite gear and all vehicles. It was later changed to a mobile science lab."