Supercheap is having a sale on their cheap enamel paint (export brand I think) and I was just wondering if that would be ok to do an engine bay with and under the sills and in the wheel wells. I've painted stuff with it before that receives daily sunlight and the paint lost its shiny finish. 

If you want a $2.99 job that you will regret everytime you open the bonnet go for it.

Not sure if id do an engine bay in this, but I went into bunnings and talked to the chick on the paint counter, she told me there are some of there anti rust/ exterior metal paints they could colour match. Ideal for under wheelarches or inside on floor i reckon.

I was just going to get a flat black or something like that, The engine bay is back now and I'm thinking of doing it again in the black. That colour match stuff anti rust stuff seems cool though! May look into it.