Solvent based acrylic (auto paint) be it from Halfords & the like in aerosol format, or in a tin from your local auto paint factor & thinned for spraying IS NOT petrol proof...…...exhaust oil resistant yes, but raw petrol left on it for any length of time will take it off.
Proper cellulose is petrol proof, but it's very hard to come by these days.
Biased I may be as we sell the stuff, but Klass Kote (2 part epoxy) is the only truly petrol proof paint I have even used. They offer a full range of standard & military colours + matt, satin & gloss catalysts. They also have a 'clear' that can be applied over most other paint types to give them a petrol proof clear.
http://www.fighteraces.co.uk/product/klasskote/Phil