Removing undercoating stuff?
 

My SC has some kind of black undercoating material around the tops of the shock towers, in the trunk. Looks like it was applied at the factory - although I can't figure out why they did that (I've also seen the same on some 914s - some had it, some didn't).

Anyways, any suggestions on the best way to remove it?

I think that stuff helps waterproof your trunk. Undercoating is removed with a plastic scraper and a heat gun.

Super is correct. However that stuff gets brittle when it gets old. You might find that using the plastic scraper and a light touch from a hammer that the stuff will just chip off in good size pieces.

For the stubborn tar remains ... Varsol or 3M Paint Cleaner on a terry cloth.