It has alloy wheels on it.If it is a Lightning. The stock tires are wide and short. If you get smaller foot print it and taller tire should save you gas. I really dont think that it is going to be much.
I drive 95% on the highways and seem to get right around 17, but I usually drive with a rather light foot (WPD is thick on Kellogg [US 54-400].) Back when 93 was available it seemed to help, but alas, no one in SC KS carries it anymore.