This article is from the The Terminator FAQ, by Karsten A. Loepelmann email@example.com with numerous contributions by others.
Molten steel is a *lot* hotter than a gas explosion; notice that the truck
not melt when it blew up. According to the "Handbook of Chemistry and
Physics", the melting point of iron is 1535 degrees Celcius. A gasoline
explosion burns at only 200-300 degrees C. Also, molten metal holds a lot
heat energy than burning gasoline.