That's if we apply what the Russians found to your car. Again we don't really know for sure.
Luckily most of us don't drive Urals or Ladas. Racist.
But I agree with you. An old non-transistorized vehicle is likely to have problems in any kind of strong EMP event. Even mil-std sheilding in military vehicles had/have quite a bit of wishful thinking to them. Lots of the electronic systems and radios in our stuff would have been tits up because there a big difference between lab conditions and the realworld.
The best bet is to keep a set electronic components in a sheilded {gore} locked box {/gore}. Needless to say, the simplier and fewer components, the better and faster your vehicle would be back up