They're supplying a product to duplicate the factory finish - which wasn't glossy. Other than "custom" colors I've not seen engine enamels that produce a gloss finish.

It could also be the conditions you're spraying in. If its too cold you won't get a shine and if its too hot the paint will dry too quickly. If you're fogging it on instead of laying on enough to be "wet" you won't get a gloss either.