[joes02tdi]

Well I just purchased a scanguage 2 used and it seems to work perfectly fine, but the mpg function seems to be way off. I own a 2002 Volkswagen jetta tdi and I have been averaging my mpg to be around 38 using the tank divided by mileage method but the scanguage is always showing around 30 even or less on the highway my commute to work is 10 miles each way and it's at around 60 mph and It reads around 27 mpg. Where is all the mileage I am getting to average the tank at around 38 if I am always getting such low mpg. Sorry if this is a stupid question im just a little confused by this.