Electric motor driven vehicles require only 1/3rd as much stored energy as a gasoline driven vehicle. That’s because the electric motors will convert the stored electricity into motive force at about 90% efficiency compared to 30% (max) for a gasoline driven vehicle.
So there is only 1/3rd as much stored energy to be released as if the vehicle had a full tank of gas.
If the idea of an electric vehicle carrying around enough stored energy to drive 500 miles bothers you, then a vehicle with a full tank of gas ought to bother you 3 times as much, right ?
The idea of a full tank of gas catching fire is not particularly comforting, either.
First, I think gas engines are only about 12% efficient. Second, I think an ultracapictor discharging would be a lot more spectacular than a gas fire.