I checked the odometer and speedo using a GPS , the Odometer was spot on over a 20Km run so no Diesel Tax issues but the speedo was another story!
Have approached the dealer, whose initial response was "not a warranty issue as it's within tolerance, but will check with Isuzu NZ."
if I try to fix it myself I will void the warranty, and putting a new $70,000 vehicle in to the dealer to have the speedo re calibrated at my expense is just not right