Originally Posted by
the evil twin
Over a couple of hundred thousand K's I found that, once calibrated, the Scangauge to be spot on with the only exception being extended 4WD on surfaces with poor traction namely soft beach or a day playing in mud.
Obviously no non-GPS instrument will work accurately in that case as the distance sensing is inaccurate IE speedo, odo, etc will all be out due to wheel slip.
When touring I found that if the Scangauge said I had used, say, 140 litres then that is what it would take to fill the tanks +/- 2 or 3 litres.
Speed was within +/- 1 KPH of GPS
Boost seemed pretty good also, certainly close enough not to warrant a separate Boost gauge
Can't speak for the EDS as I have no experience with that device.