I think they make data loggers that will do that. sadly, the scangauge will not.
it hooks into your obd2 port and it will give you trip info like trip MPG that shows you average over a trip and the likes.
definitely check out their web site
www.scangauge.com
also, some use a data logger ELM (something something) maybe you could do a search or shoot a PM to the user theholycow. he is also a moderator. I think he knows at least what I am talking about.