Dennis drives a 1993 Land-Rover Range Rover County, which appears as the most used vehicle in the series.
In "Charlie Gets Crippled", Dennis backs the Rover over Charlie, and later while driving drunk with Mac causes a crash that hospitalizes the Gang and another man.
The Range Rover gets messed up during the ill-fated trip the Grand canyon when running over a mountain bike. ("The Gang Hits the Road")
Charlie and Frank use the Rover to drive to tailgate the open tryouts Mac, Dennis, and Dee participate in. ("The Gang Gets Invincible")
After driving it into a lake chasing after a party boat, Dennis tries to sell the Range Rove for its original price so he can buy a sports car, "just me and a babe." He rejects requests to get it out of the water for a test drive, claiming it is an amphibious exploring vehicle and is apparently driven to tears by his inability to sell it. Eventually, he yells at a man who tries to buy it as a starter car for his daughter, screaming that it is a "finisher car" and "the transporter of gods -- the GOLDEN God!" ("The Gang Misses the Boat")
Following Dennis' departure from Paddy's Pub, Mac blows up the Range Rover with the RPG Rocket Launcher that he gave Dennis for Valentine's Day. ("Dennis' Double Life")
Dennis replaces the Range Rover with an identical model in "The Gang Gets New Wheels." Events in The Gang Gets New Wheels suggest that the Range Rover may be the source of Dennis' mental illness, or at least some of his more severe traits. When Dennis realizes the Rover is gone his personality changes drastically, meanwhile Dee demonstrates some of Dennis' more aggressive traits while in possession of Frank's new Range Rover. When Dennis agrees to purchase a replacement Rover, he immediately resumes the same behaviors that Dee temporarily displayed.
- Interestingly, during "Dennis and Dee Go on Welfare", he drives a Land Rover.
- The condition of the Range Rover decays over the years, with a sagging ceiling and cracking seats noticeable in "Thunder Gun Express." When Frank reimburses Dennis for the Kelley Blue Book cost of his original in "The Gang Gets New Wheels," it is worth less than $500.