Fuel Consumption Figures

[87VLCALAIS]

To get a comparison between my old VY 3.8 S and my ZB 3.6 RSV I've been tracking the the fuel consumption of both vehicles.

The consumption figures shown on the car display for the ZB are consistently 0.4 to 0.5 L/100 km less than the calculated figures using the actual fuel bought. The VY is consistently within 0.2 L/100 km. I always fill the tanks.

I know that you won't always fill to exactly the same level but the discrepancy is consistent, fill after fill after fill. It would be nice to get it a bit closer to what is being actually used.

I am familiar with fuel flow gauges used in aviation and these gauges have a "k" factor that can be adjusted to make the readings accurate. Does anyone know if there can be similar adjustments made to flow gauges in our cars?

 

[stooge]

To get a comparison between my old VY 3.8 S and my ZB 3.6 RSV I've been tracking the the fuel consumption of both vehicles.

The consumption figures shown on the car display for the ZB are consistently 0.4 to 0.5 L/100 km less than the calculated figures using the actual fuel bought. The VY is consistently within 0.2 L/100 km. I always fill the tanks.

I know that you won't always fill to exactly the same level but the discrepancy is consistent, fill after fill after fill. It would be nice to get it a bit closer to what is being actually used.

I am familiar with fuel flow gauges used in aviation and these gauges have a "k" factor that can be adjusted to make the readings accurate. Does anyone know if there can be similar adjustments made to flow gauges in our cars?

on average in my rs v6 uses 7.0~7.5 L/100km with most of that hwy driving at 100kmh so afm will be kicking in most of the time.

 

[87VLCALAIS]

I get similar figures on the cars computer, but if I calculate the consumption using litres bought and k's driven I consistently get a consumption 0.4 to 0.5 higher. A 7.5 on the cars computer will work out in reality to about 8.0

 

[stooge]

the 7.5 is not based on the computer it is based on my average of 600km per week and filling up once a week when it is below 1 quarter of a tank with the tank being a 61.7 liter tank.
i dont look at the actual liters when filling but i estimate 45 to 50 liters over 600km depending on temperature, driving style and the city/country percent.
i live in the country so most of my driving is 100~110kph to and from mine sites so afm works well for this.

i got similar consumption out of my vf ssv 6.0l with afm.

 

[Hq King]

the 7.5 is not based on the computer it is based on my average of 600km per week and filling up once a week when it is below 1 quarter of a tank with the tank being a 61.7 liter tank.
i dont look at the actual liters when filling but i estimate 45 to 50 liters over 600km depending on temperature, driving style and the city/country percent.
i live in the country so most of my driving is 100~110kph to and from mine sites so afm works well for this.

i got similar consumption out of my vf ssv 6.0l with afm.

Does this have anything to do with the speedo being out as my vf is approximately 6 kph at 1oo kph on speedo I am only doing 94 kph so in reality 12.7 ltr 1oo ks is really 12.7 ltr 94 ks . Just a thought as I don't know how it is measured

 

[stooge]

Does this have anything to do with the speedo being out as my vf is approximately 6 kph at 1oo kph on speedo I am only doing 94 kph so in reality 12.7 ltr 1oo ks is really 12.7 ltr 94 ks . Just a thought as I don't know how it is measured

It could be, the speedo in the zb is about 4 km out so i do 104 to get 100 on gps.
It will depend if the odometer is reading the correct distance.

 

[Hq King]

It could be, the speedo in the zb is about 4 km out so i do 104 to get 100 on gps.
It will depend if the odometer is reading the correct distance.

Sorry I got that abit wrong my speedo is saying 106 when doing 100 kph to me that could be saying the odometer is 6% out and the fuel consumption is 6% out as well

 

[87VLCALAIS]

I had considered the possibility of speedo error. Mine reads no more then 2 kph high at 100 kph.

I'd have thought with the electronic speedos that the error in speed would also be reflectd in the distance. When I do my manual calculations I used the trip distance from the speedo for my calculations therefore this should cancel any error due to speedo error.

 

[Anthony121]

Good to know the Odometer will always show more KM's actually driven. The Equinox was really bad with incorrect speedo showing 100KM. So bad you had to do 110 km's to keep up with cars along the freeway.

I also noticed the Fuel consumed per KM was wrong on the BH Astra, ZB Commodore and the Equinox and that was with all engine variants in the three models.

 

[Hq King]

Good to know the Odometer will always show more KM's actually driven. The Equinox was really bad with incorrect speedo showing 100KM. So bad you had to do 110 km's to keep up with cars along the freeway.

I also noticed the Fuel consumed per KM was wrong on the BH Astra, ZB Commodore and the Equinox and that was with all engine variants in the three models.

My 67 Cadillac speedo is bang on how hard is it but the fuel gauge wonders a 1/4 of a tank my vy speedo is bang on as well and fuel gauge is good the hq speedo is way out the fuel gauge is stable . I wonder if modern cars read higher to make fuel consumption look better than what they really are ??