I've just got to wonder at the logic here. It's like they gained their concept of car crashes from the movies or one of the early Grand Theft Auto games. When cars flip over or crash, they don't automatically explode. In fact, they're specifically designed not to do that ... well, except for Pintos.
Even with it being a fuel truck, something has to ignite the fuel first. If you're not in a highly statically charged environment, you're probably not going to have that ignition source. Religious types just need a crash course in basic science and probability.