I haven't tried it personally, but I understand through this forum that Castrol Super Clean (I think that's right) works really well. Easy-Off oven cleaner also works well for paint removal, but it's best done outdoors with some gloves and protective eyewear. For both materials, you need to let them soak for awhile, then wash REALLY good to remove any excess.
One question, is there some differentiation between "sprey" and enamel? If you are talking about sprayed-on enamel, or overspray, the methods above will work for all paint types...
Gip Winecoff