You can save your FJ by using two cardboard boxes: one should fit tightly inside the other, and the item to be covered should itself fit reasonably well inside the smaller box. That is about the most work involved--finding the right size boxes! The outer box is then covered with aluminum foil or Mylar, as from a cheap "space blanket." A grounding wire is then taped to the foil. I then cover the foil with black 6 mil plastic, taped securely in place, to protect the foil from ripping. At the end of the ground wire I attach a cheap small alligator clip from Radio Shack. The item to be protected is placed inside the inner box, which acts as insulation from the outer box, and any EMP hitting the foil and is bled away by the ground wire.
Alternatively, militarize all the components. You will need lots of wire braid sheathing and will probably need to wire a whole negative loom, rather than running negative earth. Isolating the electrical system from the body will allow the body to work as a Faraday cage. It will be even better if the body is earthed to the, well, Earth. (remember those grounding straps that were popular in the 80's?)
Mount a mini-gun on top with access through an after-market moonroof and you're all set for alien invasion or an outbreak of zombie-virus.