I've currently got a northane marine grade 2 pack poly waiting for me to finish making up some slats for a cast iron/timber bench seat rebuild.
I emailed and rang the manufacturer of the finish and they gave me a detailed procedure for applying the finish.
Long and short of it is that the 2 packs aren't that different, except that you eat a brush every time you do a coat (unless you use LOTS of acetone for cleaning) and that for a super-dooper-UV-stable-retain-the-grain-colour-forever-only-needs-recoating-every-5-years-finish, you need to put at least 6 coats down. So you use a lot of poly and a lot of brushes.
With the auto finishes, you'd need to make sure that they are formulated to adhere to timber - they might need a clean, grease and oil free metal to bond to chemically. The paint manufacturer normally supplies an excess of detail for most people with regards to how to use their finishes. Most people don't follow every last sodding point, which is why it can be difficult to get paint warranties honoured, as the paint system either hasn't been applied or maintained as per instructions. Then again, sometimes there is a good reason for those silly points, one would assume that the manufacturer wouldn't got to the trouble of specifying a third acetone wash or doing a Hare Krishna chant during application for the fun of it (nor testing it to make sure that the finish actually requires it).
Bear in mind that many spray metal finishes are very thin, so to build them up properly you'll be talking lots of coats.
Wattyl 7008 is a flooring finish, which means that it should stand up to a fair bit of abuse.
Wattyl also issue a handy dandy info sheet from their website:
http://www.wattyl.com.au/export/down...2509%2509%2509
assuming that that long chain of http address works.
Reading through it, it looks as though you can use over some fillers and not others. Well worth testing.
I'd hazard a guess that automotive finish is going to be metal focussed, lots of thin coats and hard as heck, so not really good for timber (too brittle).