I can dig it up, but the US govt did simulated EMP testing on 19 vehicles. Don't know why 19 instead of 20. When the EMP hit, all of the vehicles stopped running. But, after the EMP, most (17 IIRC) started right back up. Two of them needed electronic parts replaced (engine computer?). It's not as bad on vehicles and computers etc as people think.
Now, the empire's power grids would be TOAST after one good EMP burst 400 miles above Kansas...
Unfortunately, Cars are mostly made out of plastic.
But there is some protection. E.G. during thunderstorm, the car is the safest place to be.
In real world, it is hard to make perfect Faraday’s cages anyway. Even quite sophisticated shields do not protect 100%.
From what I understand most anything without a long exposed “antenna” (metal to conduct) is not likely to be seriously affected.
All that one second after stuff was fear mongering crap written for lobbyists to generate support.
I thought it was 125 miles up...