you've at least got the Duplicolor adhesion promoter but yeah getting paint that is made for cars will make things look a lot better IMHO.

 

Actually the rust o leum at my home depot has a automotive line of paints that is better quaility, I know because I've used it. It is fine as a base coat, It's more the prep work and quality of the clear coat that effects the the overall finish

 

I didn't realize that rust-o-leum made automotive paint! yeah, as long as its automotive paint it is better than any non-auto paint

 

I think it looks great!