I have been using mine for a year. It is great for resetting check engine codes on the fly and to get better gas mileage. You will have to calibrate the ultra gauge odometer to get accurate results. I used my Garmin driving on a straight road for ten miles three times to get the ultra gauge to less than 1% error. On the trip to the Florida meet I got 22mpg. It was real easy to do, just don't do anything that would be considered fun. I used almost all of my hypermiler tricks, it was a perfect day(no ac), flat ground. It was the only time in a year that I have managed that mileage. Now it is back to having fun and getting 17-18mpg.