Yes, I'm pretty sure you could buy all newly manufactured replacement parts for (say) a classic VW bug (something you can do even today) and build up a full "mage tolerant" car. Its not the date of manufacture that matters, but the technology used. Honestly, anything that doesn't have electronic fuel injection should probably be OK, though it might have other systems that get messed with (say, they used a solid state switch for the fuel pump).
I don't think you'd see a commercial car built that way, but a custom car easily could be. Heck, a lot of race cars actually are mechanical throwbacks with no "luxury" electronics in them. If you want a commercial product, you could probably find a motorcycle that was "mage reistent", and could certainly get one made,
As to electronics, I don't think "hardening" would help; I see the effect as being quantum in nature, which means it can mess up anything that uses even simple semiconductors (eg, transistors, diodes).