I’ve read so much conflicting info about this that I have decided it wouldn’t matter a bit if I were much more prepared than the average bear in terms of emp cages and what not.
After years a reading the worst case scenarios, it appears the most likely scenario would be a localized impact. From what I’ve read, most modern cars would stop, but then start up right away. Stuff in the center of an attack might fry, but in general the impact would be the same as a really bad hurricane across a territory a little larger than average in terms of power disruption—without the physical damage.
The Soviets already did an EMP attack on their own people. It did very little damage.