Fallout 3 vehicles

General information
In Fallout 3, there are no drivable vehicles. However, there are some instances where vehicles are used as a means to transport the Lone Wanderer to a new location. In the Broken Steel add-on, the player character can visit the interior of the Brotherhood of Steel's unique vertibird. It is also possible to ride an underground subway train in the Presidential metro during the main questline. Traveling to Point Lookout is done on a ruined pre-War ferry, "the Duchess Gambit." The player character is also required to use a railroad hand cart to enter and exit The Pitt, as the tunnels are too dark and numerous to navigate on foot.

Derelict vehicles
Although there are no drivable vehicles in Fallout 3, there are hundreds of explosive derelict vehicles. After two hundred years of neglect, their defunct nuclear reactors are highly volatile and prone to exploding if damaged. Once a vehicle catches fire an explosion is inevitable, but more damage will hasten it. The explosion will make an area of approximately 10 feet around the car radioactive for a few seconds, this can make most vehicles extremely dangerous to take cover behind as raiders and super mutants can easily blow up the vehicles with their bullets.

There are a variety of derelict vehicles dotting the roadways; most are large sedan-sized cars, though there are smaller, one-person cars. Heavy semi-truck tractors also can be seen which take slightly more damage to detonate but create an explosion slightly bigger than other cars. Buses are also encountered, and their explosions are particularly large and devastating, more than twice the size of an explosion created by two cars. Smaller vehicles like motorcycles and street cleaner machines can be shot and blown up, but they do not produce a mushroom cloud explosion. In fact, their "explosion" is extremely small and short, even smaller than a frag grenade/mine explosion. Often, vehicles in close proximity will set each other off in a chain reaction.

There are some derelict vehicles that will not explode no matter how much weapons fire is poured into them. One can discern these from the more dangerous variety by examining the trunk; if the hatch is missing and one can see an empty basin in the back, the reactor is no longer present.