Welcome to the site. Its good to see someone who gets paid for mileage looking to cash in. I see a lot of guys just brush it off saying "the company pays for it, so who cares?"
My suggestions to you would probably be to look into a grill block as you're likely on the highway quite a bit. It'll also help with warm up times. I'd also suggest pumping your tires up to the max sidewall rating as this'll reduce rolling resistance. Other than those few things, I'd also look at picking up a
scangauge or
mpguino. It'll really allow you to evaluate your driving and really dial it in.