FIRE right above fuel tank
 

Just purchased 2009 Volvo C70 for my 89 year old mother. Was driving it from dealership to deliver it to her (only made it 40 miles from the dealership) - stopped to 'empty out' and thick smoke starts bellowing out from the right rear undercarriage. Someone ran over, looked beneath the car and said there was a fire (RIGHT ABOVE THE FULL FUEL TANK, no less) Dealership says, "cars catch fire" - UNBELIEVABLE!!!! SEE photos - does anyone know what may have happened and identify the part(s) shown in burn area surrounded by what appears to be honeycomb insulation or something? Dealership had JUST replaced ONE strut - same side as fire, right rear - could it be causal? I need help!!!!!!

That's the muffler, not the fuel tank. And no, nothing related to a rear shock would cause this.

FIRE near full fuel tank!!!
 

So, any idea what would cause a fire to start at that point by that part?

Hard to tell what the picture is of, but something from the road could have gotten caught between the muffler and heat shield.