The milage on my 2003 prius was about 42 mpg average. After I put in the enginer system it has gone up to about 62 mpg. Because we live on a mountain and my house is at 1500 feet above sea level we go up and down a lot. On a trip from my house down to sea level and then back up to my house I get about 62 mpg. If I just drive on the flat land I get more like 80 mpg.
