"...if the road turns into the tornado's path..."

In that case I would do a "dynamite turn" and haul in the other direction. I know that might not save you, but ya gotta try something. A freeway overcrossing would probably be about the only place you might be able to sit out a twister in a vehicle. Personally, I will take the CA earthquakes any day over a tornado. And in about a year we will be heading into that part of the country...