this is because the fuel sensor is place on behind the fuel tank.wen you are ascending,the fuel goes on rear on tank and shows more fuel than actual and vice versa.My khyber has sensor on left side of tank so when i turn right,more fuel is shown and less when i turn sharp left..similarly,when i accelerate,the fuel gauge goes down and when im stopped at signal,fuel gauge rises very minute.its all because the gauge shows approx amount of fuel and not cent percent.