For semi-truck enthusiasts, the Mack Super-Liner offers a huge sleeper cabin. With the passenger mod, a second player can "sleep" in the back or watch the road from the co-pilot seat while you back up a B-double trailer into a tight grain elevator.

Even with a great mod, things can go wrong. Here are the most common errors and fixes.

At its core, the (often referred to as the "Universal Passenger" or "Ride Along" mod) is a script mod. Unlike a standard vehicle mod that adds a new tractor to the shop, this script modifies the game’s core logic. It allows one or more additional players (AI or human) to sit in the passenger seat of a moving vehicle.