[smc]

That is interesting. It was not a fuel leak by the looks of it. The fuel filter is intact as well as its hoses. The fuel lines themselves are run in the cab. So a leak anywhere there would have caused a fire in the cab. There is Very little engine damage. Which leads me to believe that the fire itself did not originate in the engine bay. Most of the plastic is in tact. The fuse panel is intact as well. Normal damage to the battery, not showing a sign of a massive electrical fire.
The rear tire is popped but not the font. Along with that, the discoloration of the steel also tends to say that the fire was burning longer, and hotter in the rear of the car.
If the fire started in the drivers side rear, then its doubtful that it was an electrical fire, as there is really nothing on that side to ignite with a short.

Im really tempted to say that the e-brake was left on and over heated the rear brakes, and ignited the wheel well rubber splash guard.

I want to rule out the rear exhaust at its not hot enough to ignite anything automotive fluid wise..

Or the simple explanation. They parked on top of something flammable. Dry grass or the like. And the exhaust ignited that, the fire then crept forward.