How do I move wrecks?

I found a gas station and now have a flatbed truck to loot with.

There is a motorbike without wheels in front of the petrol bowsers though. How do I move it so I can fill up my truck easier?

Also, do I need to line up the gas tank with the bowser? or just have the truck adjacent?

Smash into the motorbike and hope it does not make the pumps explode.

you can be right next to the pump or one tile away

Yep bumping into it is the easiest way, you can also disassemble it which would take longer. You only need to be adjacent to fill up, just stand between the pump and the vehicle.