Yes, no one really knows how much damage an EMP would do.
The grid going down is my numero uno fear. There are 9 major substations that if taken out would put the grid down. I’m more worried about that and a cyber hack than any EMP. The grid will likely go down at some point but EMP is way down on the list of causes.
Plus if the grid does go down it will likely be the NE grid. That would leave the other two in place. But even a few mos without electricity would be pretty bad.
I think an EMP would take out the power grid in a lot of areas, as for cars I think it wouls take out about 1/2 of them, some ov the newer ones might make it just due to the fact that most cars are metal shells and most would reflect a large amount of the EMP discharge, also if they were in a grage at the time and the hosue was insulated with that foil backed insulation they would fare better.