[cole_han]

I had my disco sport for a little under a year now and I've noticed that the trip computer always over estimates the mpg and just wanted to see if you all have encountered similar situations? Last trip I took (mostly highway for a snowboard trip to Mt. Baker) averaged 21.5 mpg but the trip computer said 24.6 mpg. That's over a 100 mile less if using a full tank!

 

[Bill F]

Reported several times use search

My car was originally out 14% then after a new set of injectors it is out 20%

 

[dulci2se]

Reported several times use search

My car was originally out 14% then after a new set of injectors it is out 20%

Tyre size may affect MPG calculation, not sure it should be that far out though. There is a tyre calibration on the Autel AP200 scanner. When I’ve worked it out on previous cars it’s been pretty near to what I calculate. Haven’t done it on my present Discovery Sport. Suppose the fuel flow sensor could also be at fault.

 

[Bill F]

There is no fuel flow sensor which be could possibly more accurate. Cars use pulse width to estimate the amount of fuel being used at a set pressure. Higher or lower pressure, can make a difference and the manufactures always error on their side. Most consumers can not do the math to to calculate MPG or L/100KM so the onboard computer gives them bragging rights. Diesel engines (new) give extra pulses when in regeneration mode, hurting fuel economy and the extra fuel dilutes the engine oil.

 

[dulci2se]

There is no fuel flow sensor which be could possibly more accurate. Cars use pulse width to estimate the amount of fuel being used at a set pressure. Higher or lower pressure, can make a difference and the manufactures always error on their side. Most consumers can not do the math to to calculate MPG or L/100KM so the onboard computer gives them bragging rights. Diesel engines (new) give extra pulses when in regeneration mode, hurting fuel economy and the extra fuel dilutes the engine oil.

Ok thanks for that...it is always preferable to work out yourself rather than relying on the cars mpg display. Having said that the ones I’ve come across and have worked out before, have always been pretty close to calculated.

 

[dulci2se]

There is no fuel flow sensor which be could possibly more accurate. Cars use pulse width to estimate the amount of fuel being used at a set pressure. Higher or lower pressure, can make a difference and the manufactures always error on their side. Most consumers can not do the math to to calculate MPG or L/100KM so the onboard computer gives them bragging rights. Diesel engines (new) give extra pulses when in regeneration mode, hurting fuel economy and the extra fuel dilutes the engine oil.

My apologies, no there is no flow meter, not on my diesel engine anyway, I know that some vehicles do have them...think the 2.2 diesel (Ford derived) may have one, but maybe not used to calculate fuel MPG. The quoted manufacturers figures do not seem to be very accurate, the ingenium diesel is supposed to do 53mpg on a run, but the very best I’ve managed is 50 and that may not have been accurate.