There is one way to solve this problem. Use charcoal. 
Sparky when I was doing my article on grill safety I came across a true story.........This is hard to believe but I must guess there was lots of adult drinks involved.
Two guts were ready to go into a game so they put their charcoal grill into the trunk of their car.
Still lit!
I guess they thought the air would run out or they were not thinking at this point.......they took a few cars with them on that move.
What I would do even as a young fan that had a few drinks was
1) line my grill with two layers of foil,
2) when done I had brought water I would put out the fire with water.
3) Take the foil out & toss it
4) water down the grill a second time
5) wait until it was cold.
6) inspect it
7) Keep it under the car for the game or as the grills got more expensive in the trunk.
when ready to leave put it in the trunk if it was not already.
there was not a piece of ash on that grill when it went inside the car
