Re: Who uses their Smartphone as a HUD?
As info, I read somewhere that auto manufactures have always calibrated their speedos on the fast side so they would not be blamed for a owner's ticket if they tell the officer the speedo said something different. I noticed this with my wife's Hyundai - it's ~3 MPH faster than the GPS. On the xfire, it's almost perfect.
Also, I too have a ultra gauge and after calibrating the distance and the gas, it's very accurate on average MPG and DTE. I really like that little gauge for $60.