Best keep it that way and not work on 'em in the backyard. My neighbor who's a body repair man, tells about an insurance adjuster who was electrocuted by a short in a Prius. Perfectly safe as long as you're not laying metal objects (his clipboard) across parts of the internals, after it's been crashed.
Of course it could be an urban legend, but he told it like he heard it from someone who worked at the shop where it happened.