PureTech 180 - Real fuel consumption vs board computer

[zakazak]

Hi there,

I recently bought a C5 Aircross from 2020 with 34.800km and have been driving it for 2 months now with a total of 2.050km. I am mostly driving in city traffic with lots of stop and go and there for have a high fuel consumption (but I think it is still too high anyway!). What bothers me even more is the the difference between the real fuel consumption and the one reported by the board computer. Never before did I have such a big difference in fuel consumption measurements.

Avg fuel consumption 2.050km: 8,73 l/100km (based on my own logging).
Example fuel consumption with my own logging vs board computer:
Own logging vs board computer (in l/km):
9,17 vs 8,50
8,31 vs 7,60
8,57 vs 8,10
9,08 vs 8,10

Basically the board computer show about 0,5 l/km lower fuel consumption than real life logging reports!
I am doing the same logging/comparison that I have been doing with 3 different cars in the past over 350.000km of comparison. I log the distance driven and the fuel that I put into the tank. I do a full tank until the automatic stopping function stops the fuel flow. I then wait 10 seconds and start the fuel flow again until it stops automatically once more.

Does anyone here have the same experience?

Thanks!

[Citfan151]

We have the current model C5 Aircross with the 133Kw/250Nm 1.6L motor. At best on a City cycle it returns 8.2L/100Kms (per onboard reading). Sometimes north of 9.0L/100Kms. Advertised Urban consumption is 6.3L/100Kms. So, at best, our fuel economy is 30% higher than advertised consumption. In one review, I saw an actual figure of more than 10.5L/100Kms (or 66% higher than advertised). Your analysis just makes all this worse.

Our 2012 C5 3.0L HDI gets much better fuel economy (including 4.9L/100Kms on highway), even though it weighs about 300Kgs more and has nearly double the torque.

Have never understood why they replaced the kind of motors we had with over worked lawn mower motors

[zakazak]

We have the current model C5 Aircross with the 133Kw/250Nm 1.6L motor. At best on a City cycle it returns 8.2L/100Kms (per onboard reading). Sometimes north of 9.0L/100Kms. Advertised Urban consumption is 6.3L/100Kms. So, at best, our fuel economy is 30% higher than advertised consumption. In one review, I saw an actual figure of more than 10.5L/100Kms (or 66% higher than advertised). Your analysis just makes all this worse.

Our 2012 C5 3.0L HDI gets much better fuel economy (including 4.9L/100Kms on highway), even though it weighs about 300Kgs more and has nearly double the torque.

Have never understood why they replaced the kind of motors we had with over worked lawn mower motors

I am curious if your 8,2 onboard reading results in 8,7 real life consumption.

Yesterday I did 500km.of highway driving (150km/h) and ended up with 7,8L onboard reading and 7,7L real life consumption.

[Beanee3]

Problem with this comparison is how do you know that the fuel added to determine how much you used is 100% accurate each time. I fill mine up till the second click and record the litres. Then I note the figures from the onboard computer, miles travelled since last fill, set to zero each time, mph. MPG and total mileage.
I also note the readings as shown on MyCitroen app.
There is always a difference in my worked out mpg and that on the car and that in the app.
If the car is not in the same position,ideally level when you fill it, the amount taken from the pump will differ. The weight of your right foot on the pedal. Where you drive, urban or country roads etc etc all have an effect plus how many passengers or goods in the car.
My C3 automatic returns around 38.5 mpg by my calculations but 40 to 42 on the car computer and MyCitroen app.
Sadly this is one of the cost of owning a car. Maintenance, depreciation and insurance being the others.
You just have to accept these things and live in peace with your car.

[zakazak]

Problem with this comparison is how do you know that the fuel added to determine how much you used is 100% accurate each time. I fill mine up till the second click and record the litres. Then I note the figures from the onboard computer, miles travelled since last fill, set to zero each time, mph. MPG and total mileage.
I also note the readings as shown on MyCitroen app.
There is always a difference in my worked out mpg and that on the car and that in the app.
If the car is not in the same position,ideally level when you fill it, the amount taken from the pump will differ. The weight of your right foot on the pedal. Where you drive, urban or country roads etc etc all have an effect plus how many passengers or goods in the car.
My C3 automatic returns around 38.5 mpg by my calculations but 40 to 42 on the car computer and MyCitroen app.
Sadly this is one of the cost of owning a car. Maintenance, depreciation and insurance being the others.
You just have to accept these things and live in peace with your car.

I described the process of filling up and making sure it is the same everytime. I have been doing this for 10 years, it works well.

[Beanee3]

Ok it was just an observation.

[zakazak]

I am now trying out eco mode. It feels a lot smoother and less aggressive so I hope that this might help with consumption. A bit annoying that you can't start the car in eco mode though.

[zakazak]

So I just did another highway drive (600km). I did the same route that I already did previously but now with eco mode. The results are shocking.
Without Eco Mode: 7,7L / 100km
With Eco Mode: 8,4L / 100km

Makes absolutely no sense. Same route, same traffic, same load.

[zakazak]

If anyone gets here: It seems like the panoramic roof causes a higher fuel consumption during the summer.
To fix this, just close the panoramic roof with the fabric lid.

[Juan Sheet]

What did you expect?

Not sure you need to be a rocket scientist to work that one out...