One part Appeal, and two parts water.
It is our 'go to' dressing for everything except tires and wheel wells.
While, yes, it is great in the engine bay, we like it on all interior (hard) surfaces.
Leaves a low luster finish; parts look fresh and new, but not 'shiney'.
Malco is in Barbeton, OH. I dunno about online stuff from them. I hve a route driver who stops by every two weeks. I particularly like their:
Leather and Plastic Cleaner (Quite strong, cut it 1:1 with water) Good for stubborn, dirty leather seats.
TRUE GRIT This is the most aggressive compound we have in the shop. We use it with rotary and a big ol' honkin wool pad (old school - really works) Fixes 1500 grit sanding marks, and really cleans up a 10 year old paint that has been neglected. Expect some swirls -you'll have to go back over every surface with a fine polish. If True Grit doesn't get it, we either STOP, or resort to wetsanding...
SapSucker Great for Tree Sap. Allow it to dwell - be sure to use MF towels when rubbing to remove!
A quality line, but I certainly have not tried all their stuff .
When I was starting out (not so long go) I found that the frequent visits from the route salesman were quite helpful in my education, and actual problem solving.
Jim