The lowest estimate I could find of the voltage of a lightning strike was at around 10MV - Yes, that's a big M - the lowest estimate I could find. All of the rest of them put it at at least 100MV.
Take for example, 3M insulating rubber, which has a dielectric strength around 700V/mil, you would need about 14 inches of that insulating rubber to block 10MV. That pickup truck would have to be encased in a ball of solid rubber - 140 inches (about 3.6m) thick, to be on the safe side.
If the truck's windows were made of steel, you'd get a faraday cage out of the cab. What saved that couple is the fact that the truck body is much, much more conductive than the people and the air inside it. And the fact that the gasoline in the tank is liquid, not a gas - note the 2nd burn of the exhaust gases.