I like "Marhyde" (spelled something like that anyway). I get it at my local Ace hardware. It's essentially just tar in a spray can. Applies well and has good coverage. It's not a "plastic" product so you actually have a chance of removing it from unwanted places such as ; brake rotors, exterior body parts, floors and exposed skin.

It's still a nasty job. The temperature needs to be in the upper 70's to the 90's for the best coverage and penetration.