I had a short tank ,, 300 miles or so that came in at 50.53 mpg this week after I installed a engine belly pan. Im currently at 50.7 mpg on this tank in the Civic. I just drove into work with my best segment to date at 54.8 mpg. Saw a spike of 56 mpg on the SG. I think I will be ordering the HCHII undertrays before to long. This is 90% hwy driving trying to keep ice on speeds between 55 and 60 mph and of course useing all the other tricks of the craft in the book.