PureTech 180 (C5 Aircross) - Real fuel consumption vs board computer

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zakazak
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PureTech 180 (C5 Aircross) - Real fuel consumption vs board computer

Post by 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!
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Re: PureTech 180 (C5 Aircross) - Real fuel consumption vs board computer

Post by GiveMeABreak »

The information from the vehicle is calculated based on all the prevailing conditions of the driving at any particular time, like the gear you are in, the engine temperature, the electrical consumers, heating settings, Air conditioning, wind, fuel load / weight, speed etc., so no 2 journeys will be the same.

Always make sure you are using the AVERAGE readouts, not the 'Instantaneous' readings as this does not work below 30 KMH.

Lastly, you can only compare vehicle with vehicle (that is to say the same vehicle with the same engine) for any sort of comparison and not with another vehicle style and engine, or transmission for example.
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Re: PureTech 180 (C5 Aircross) - Real fuel consumption vs board computer

Post by zakazak »

GiveMeABreak wrote: 26 Jun 2024, 17:27 The information from the vehicle is calculated based on all the prevailing conditions of the driving at any particular time, like the gear you are in, the engine temperature, the electrical consumers, heating settings, Air conditioning, wind, fuel load / weight, speed etc., so no 2 journeys will be the same.

Always make sure you are using the AVERAGE readouts, not the 'Instantaneous' readings as this does not work below 30 KMH.

Lastly, you can only compare vehicle with vehicle (that is to say the same vehicle with the same engine) for any sort of comparison and not with another vehicle style and engine, or transmission for example.
I am using the average display of course.
Trip A is since I got the car
Trip B always resets when I fill up the tank.

I am comparing the difference between the fuel consumption that the board computer reports and what I log in real life.
The difference is 0,5 l/100km which is huge compared to other cars. So the board computer on the C5A must be really bad or I don't know what is going on.
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Re: PureTech 180 (C5 Aircross) - Real fuel consumption vs board computer

Post by PaulC5 »

On the PSA cars we've had the trip computer stops going up at 9999 km (6214 miles) and anything after this can not be trusted. So if you are at this distance you need to reset it by pressing on the end of the wiper stalk. To be only getting about 32 mpg (8.8 l/100 km) is a bit disappointing, you must be doing mostly stop/start short trips. A diesel would be better if it did not have an exhaust dpf with your short trips.
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Re: PureTech 180 (C5 Aircross) - Real fuel consumption vs board computer

Post by zakazak »

PaulC5 wrote: 26 Jun 2024, 22:12 On the PSA cars we've had the trip computer stops going up at 9999 km (6214 miles) and anything after this can not be trusted. So if you are at this distance you need to reset it by pressing on the end of the wiper stalk. To be only getting about 32 mpg (8.8 l/100 km) is a bit disappointing, you must be doing mostly stop/start short trips. A diesel would be better if it did not have an exhaust dpf with your short trips.
I know about the 9999 limit from my previous C5.
I didn't choose Diesel especially because of DPF as my trips aren't short but with a lot of stop&go on the highway. 99% also too short stops for stop&go to activate. But 20km take me about 30-50 minutes.

Yes the mpg is really disappointing which is also why I am wondering if smth is wrong.
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Re: PureTech 180 (C5 Aircross) - Real fuel consumption vs board computer

Post by 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.
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Re: PureTech 180 (C5 Aircross) - Real fuel consumption vs board computer

Post by GiveMeABreak »

Of course the driving mode will affect economy as depending on equipment (gearbox, drivetrain etc.) this can affect how soon and at what engine speed the gears are changed on an automatic for example.

It may help if you pop your VIN up so I can see exactly what you have. Please post your VIN in full without spaces - it will be automatically masked from public view after submitting your post & will only be visible to staff.
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Re: PureTech 180 (C5 Aircross) - Real fuel consumption vs board computer

Post by zakazak »

GiveMeABreak wrote: 02 Jul 2024, 19:47 Of course the driving mode will affect economy as depending on equipment (gearbox, drivetrain etc.) this can affect how soon and at what engine speed the gears are changed on an automatic for example.

It may help if you pop your VIN up so I can see exactly what you have. Please post your VIN in full without spaces - it will be automatically masked from public view after submitting your post & will only be visible to staff.
Hi there, VIN: VR7**************[VIN obfuscated, can be read by forum staff]
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Re: PureTech 180 (C5 Aircross) - Real fuel consumption vs board computer

Post by GiveMeABreak »

C5 AIRCROSS (C84) 5-DOOR CROSS OVER 1.6 PureTech 16v 180 (EP6FADTXD Euro 6.2) STT TYPE 8-SPEED AUTOMATIC GEARBOX

Just thought this may be useful to give the stated official figures for litres per 100kms and some other info.

I've included a 1.2 Puretch, your vehicle in the middle and a 2.0 HDi Diesel all from the same year (2018) with same Euro standard (6.2).

As you can see even with different tyres fitted there are small differences
17 & 18 Inch Wheels1.2L PureTech 130 S&S 6-speed Manual1.6L PureTech 180 S&S EAT8 Auto2.0L BlueHDi 180 EAT8 S&S EAT8 Auto
Maximum speed (mph)117134131
Acceleration 0-62 mph driver only (sec)10.58.28.6
Urban drive cycle MPG (litres/100km)46.3 (6.1)39.8 (7.1)53.3 (5.3)
Extra Urban drive cycle MPG (litres/100km58.9 (4.8)57.6 (4.9)61.4 (4.6)
Combined drive cycle MPG (litres/100km53.3 (5.3)49.6 (5.7)58.9 (4.8)
Regulated Emission StandardEuro 6.2Euro 6.2Euro 6.2
Carbon Dioxide (CO2) emissions (g/km121131126

19 Inch Wheels1.2L PureTech 130 S&S 6-speed Manual1.6L PureTech 180 S&S EAT8 Auto2.0L BlueHDi 180 EAT8 S&S EAT8 Auto
Maximum speed (mph)117134131
Acceleration 0-62 mph driver only (sec)10.58.28.6
Urban drive cycle MPG (litres/100km)46.3 (6.1)40.4 (7)54.3 (5.2)
Extra Urban drive cycle MPG (litres/100km60.1 (4.7)57.6 (4.9)62.8 (4.5)
Combined drive cycle MPG (litres/100km54.3 (5.2)49.6 (5.7)60.1 (4.7)
Regulated Emission StandardEuro 6.2Euro 6.2Euro 6.2
Carbon Dioxide (CO2) emissions (g/km119129124

18 inch Wheels with Mud & Snow Tyre1.2L PureTech 130 S&S 6-speed Manual1.6L PureTech 180 S&S EAT8 Auto2.0L BlueHDi 180 EAT8 S&S EAT8 Auto
Maximum speed (mph)117134131
Acceleration 0-62 mph driver only (sec)10.58.28.6
Urban drive cycle MPG (litres/100km)47.1 (6)39.2 (7.2)53.3 (5.3)
Extra Urban drive cycle MPG (litres/100km57.6 (4.9)56.5 (5)61.4 (4.6)
Combined drive cycle MPG (litres/100km53.3 (5.3)48.7 (5.8)57.6 (4.9)
Regulated Emission StandardEuro 6.2Euro 6.2Euro 6.2
Carbon Dioxide (CO2) emissions (g/km122132128
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Re: PureTech 180 (C5 Aircross) - Real fuel consumption vs board computer

Post by zakazak »

Thanks for that! It is probably hard to argue how much those values relate to real life but at least they give a sense of feeling for it.
I previously had a HDI 165 C5 from 2011 (2.0L with 163 PS) that I can compare it with from real life experiences.
I am shocked to see how much less the HDI seems to consume in urban/city driving. Maybe I should have really gone for the HDI instead of PureTech.
But then I also don't know how much off those HDI values are from real life consumption.
As a comparison, my urban/city driving consumption for the last 3 fill ups was 8,31L + 8,57L + 9,08L.
I would say that make 1,5L of a difference compared to what the official figures state.
But that is also without eco mode - which might have been used in the official figures testing.
It makes sense that 17" & 18" have a higher consumption than 19" since the 19" are less wide tires compared to 17" and 18" (so 19" has less contact surface).
Last edited by GiveMeABreak on 03 Jul 2024, 12:39, edited 1 time in total.
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Re: PureTech 180 (C5 Aircross) - Real fuel consumption vs board computer

Post by GiveMeABreak »

Just thought it may show how economy can be affected by tyres alone! The newer 8 speed gearboxes are supposed to be more efficient, but a recent new C4 petrol I had for a few days with EA8 absolutely guzzled fuel. I'll stick with my clean diesel for as long as I can.
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