I guess you just can't gas it up
Marty McFly: [looks through a camcorder] This is heavy-duty, Doc. This is great. Uh, does it run, like, on regular unleaded gasoline?
Dr. Emmett Brown: Unfortunately, no. It requires something with a little more kick. Plutonium.
Marty McFly: Um, plutonium. Wait a minute. Are...
[lowers the camcorder]
Marty McFly: Are you telling me that this sucker is NUCLEAR?
Dr. Emmett Brown: Hey, hey, hey! Keep rolling. Keep rolling there.
[Marty raises the camcorder]
Dr. Emmett Brown: No, no, no, no, no, this sucker's electrical, but I need a nuclear reaction to generate the 1.21 gigawatts of electricity I need.
Marty McFly: Doc, you don't just walk into a store and-and buy plutonium! Did you rip that off?
Dr. Emmett Brown: Of course. From a group of Libyan nationalists. They wanted me to build them a bomb, so I took their plutonium and, in turn, gave them a shoddy bomb casing full of used pinball machine parts. Come on! Let's get you a radiation suit. We must prepare to reload.