Is there a way to tell if I have a different tune loaded?

[dcs1968]

Ok so I have to explain why I even am posting this question. I bought this 2010 truck in my signature over 4 years ago with 115k on the clock. It was a one owner vehicle according to the carfax report. I have put an additional 50k on it and absolutely love this truck! Everything under the hood looks stock and I have passed California emissions testing twice so far no problem. No CELs since I have had it and averaged 14 mpg unloaded for the most part. Now hear is why I am asking.... I live in SoCal where people think they are driving NASCAR on the freeways so I usually go 75-85 mph which would explain the mpg. So the last couple times driving to work 40 miles each way I have been staying 65-70 mph and have been averaging 21 mpg! Total shock as I have never seen those numbers. I am just wondering if it is possible that the original owner could have had it tuned where the emissions equipment was left intact? The mpg figures I see most people post is 13-15 for a 2010-2012 set up like mine so I figured what I was getting was normal but when I slow down and drive the speed limit it gets considerably better. So is there a way to check if the tune has been changed?