I won't even elaborate on Korean stuff vs. American stuff anymore since those who bash domestics seem to think
all American cars are junk due to a few rotten apples along the way. Yet Kia has never made any junk cars. Neither has Honda...or Toyota...or Hyundai...not even Yugo....only GM, Ford and Chrysler.
I seriously doubt the sun could light off a firework; it would have to get awfully hot to ignite. Maybe if a magnifying glass were placed over it. Most likely some clown was lighting them off and dropped one down in the seat and it went off. Yeah I know I did it once too when I was a teen on New Years eve throwing lit bottle rockets out the window....and one went down the side of the door panel under the seat instead of out the window...didn't set the car on fire but my buddy sarcastically said I almost gave him a heart attack when the report went off.