Part of the reason most vehicles wont sustain permanent damage is due to the length of the wires involved. Most of the power from an EMP would be in longer wavelengths. Which means you need wires 40+ feet long to readily pick it up, and convert the EM energy to an electric charge differential. Microprocessors are vulnerable to shorter wavelengths (think microwaves). But those wavelengths are readily blocked by thin metal (like the mesh on your microwave door window). The complex microprocessors used in eletronics are vulnerable to voltage transients on the input/output wiring. Which is why all vehicle electronic modules incorporate protection circuitry to suppress these transients. Obviously its not foolproof, but provides a good level of protection against transient extreme events. For example a lightning strike 100ft away, or a high altitude nuclear detonation.
If the OP is interested in a vehicle that is EMP proof for other reasons (say simplicity of repair in the field, etc), There is nothing wrong with that. However, if they are focused on prepping for one of the conspiracy theory driven apocalypse scenarios... Well, this is a public forum, and ridiculous ideas will inevitably draw ridicule.
Literally the first thing to fail in an EMP scenario is the power grid. The long transmission wires will become charged with millions of volts, the resultant arcing will destroy switching equipment, and transformers. The complex fuel refining and distribution systems will not be far behind. You simply can't run a refinery without grid electricity. Fuel supplies would be depleted in a few weeks, and vehicles would rapidly become useless. If a significant portion of vehicles become immobile, major highways would be impassable anyways.
With no fuel food supplies will dry up in a matter of weeks as well. And you can't just plant more crops at the drop of the hat...