An independent documentary called "Pretty Dyana" captures the story of how Roma (gypsies) in Belgrade find old Citroen Dyana cars and modify them into mini-trucks that haul recycled cardboard.
They do this primarily by stripping the cars of everything except their motors, chaise, and steering wheel. Everything else goes. The Dyana is particularly suited for this, the Roma say, because the frame remains intact after you take everything else away. So they can easily add a bin on top of the back. And presto, now they have a cardboard hauling cart.
And because it doesn't look like a car anymore, it fits into some grey zone with the police. Not that they don't get fined for driving it around. All this and more about how the Roma survive in Belgrade is presented in this nice short documentary.
Note the plastic bottle gas tank.