My coolmax has been getting 54-58 mpg on my 8.2 miles trip to work. Today the coolmax flipped its lid. I actually saw a 74.2 mpg. I filled up May 15. Today is June 14. The coolmax still has quarter of a tank. When I was driving my Ranger, 4 cylinder automatic trans. I needed to fill up every week, same trip to work. Definitely an improvement. 49.3 on this tank,so far.