you will have a hard time finding automotive colors with Vallejo paints ,,, they are clearly geared for armor, figures and airplanes.
so no matter how good they are, does not help the automotive modeler much .
Tamiya has a better selection but still mainly the basic spectrum ,, nothing fancy but excellent paints
Auto air has all the great finishes , metallics, pearls , candys , lots of great options.A lot of pro graphic guys use it.
I use createx for the general stuff but, step up to auto air , or even the popular solvent based paints for painting high gloss body finishes.
Createx has some really nice colors for that also, but not as expansive and foolproof as auto air.
Createx is good and cheap paint to practice with and easily found almost everywhere
for brushwork I would go with a good brushing paint and shy away from the airbrush ready versions.
I'll second DD on the createx cleaner/conditioner ... it rocks,,, and keeps the airbrush running smooth, rather than just stripping it dry like thinners will...or,A small bottle of airbrush lube is worth the investment.