If you're not math retarded it is quite simple. There are super-chargers on all highways and the thing basically tells you which one to charge at.
I'm a busy man - a man of leisure. So instead of getting out to stretch your legs every 4 hours, you do it every 3 hours. It is far far better to have it drive you. You can totally watch everything go by. I have a rubber-banded bracket I put on the top of my steering wheel... tinted windows. I just kick back and watch movies.
Long drives are the best as is being stuck in traffic. In traffic it'll just constantly pace. In long drives you can totally kick back because it drives on the highway just fine.
I can drive 5 hours to a casino better than anything in LV and watch a movie - not have to deal with an airplane or airport.
Only thing I agree with singer is there is simple common sense involved in whether to buy one.
If you have the dough and build out a real solar system you don't even have to depend on others for fuel anymore. Harder to repair but need so fewer repairs.
Singer would be hard pressed to find any reasonable trip he ever takes to not be readily chargeable.
I agree though if you are relying on a single charger...
You can always pack a generator in the trunk lol.