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C6 Fuel consumption

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Sun Jun 05 2011, 06:56pm
Joined: Sep 20 2010
Member No: #238
Location: Aldeburgh
I've just done 500 miles in mine, mostly on motorways, mostly with cruise control set at 75mph. 2/3 people, no hard acceleration/deceleration. Average speed was 48mph. Result-33.6mpg. Whilst this is not bad for a big car, etc, etc, it's so far outside Citroen's figures that I tend to wonder!

I bought the car secondhand. I (idly) played with the consumption figures on the Navidrive. The last set (up to the time that it became mine) gave 620 miles at, er, 22mpg.

Why I ask, is that someone else has got 40mpg out of a 2.7, in conditions not so very different from mine. Does anyone have a 2.2 auto for comparison, or is there something I could do (or get done, more like!) to improve matters.

Sun Jun 05 2011, 07:03pm
Joined: Jan 18 2011
Member No: #345
Location: Woodbridge
I get about 34mpg average out of my 2.2 manual which is meant to be more economical than the auto. There's quite a lot of short distance semi-urban driving in that, but still I haven't got more than 40mpg even for long motorway journeys. I reckon the 2.2's quoted economy figures are way off what you actually get.
Sun Jun 05 2011, 07:16pm
Joined: Sep 20 2010
Member No: #238
Location: Aldeburgh
Oh, dear! (Or, bu**er!)

So, in lieu of the lower road tax, is much worse economy. Thank you!!!
Sun Jun 05 2011, 07:38pm
Joined: Apr 06 2010
Member No: #82
Location: Maidenhead
My MPG is constantly around 30/31mpg. Normally two trips of an hour plus a week, and 5 trips of about 15 mins.
Sun Jun 05 2011, 07:45pm

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
With the same 2.2 'lump' in the C-Crosser we were averaging around 33-34 mpg and that was a manual.
Sun Jun 05 2011, 07:58pm
Joined: May 18 2010
Member No: #119
Location: Woodbridge
My total average over 16k miles is currently 30.6 (i never reset one of the trip counters). This includes 8 miles per day to work most days, with around 2 long c. 500 mile trips per month.

On a long motorway run, I generally get an indicated 35-38 mpg. Calculations based on "fill, drive and re-fill" I performed last year over two 500 mile journeys on consecutive weekends suggest this could be 2-3 mpg out.

Even so, 33.2 mpg, which was my calculated average, to transport myself and family, in serene comfort, from Woodbridge to Wigan, return, including trundling about to visit friends and relatives, and all queues, fixed/average speed limit sections on the A14, roadworks on the M6, the M6 toll, etc., doesn't seem too bad.

I have to note that this is better than my Citroen XM 2.0 CT Estate (petrol) ever managed in the 9 years I owned it which would get 26-28 on the same run. It may have scraped into the 30s early in its life, but generally it was always 20s.

Even my 1.6 BXs on the same run used to generally be in their late 20s/early 30s.

I can honestly say that whilst I have up-sized my cars in the last 20 years, the fuel consumption on the Wigan-Woodbridge journey has remained remarkably similar.

I can push it to around 44mpg in my wife's MB C220, and even a very trendy Honda CR-Z I had for a weekend, and even with the brilliant Hybrid IMA Tech, I was only managing 42-44mpg on the shortish dual-carriageway runs I got the chance to use - but it was much better "around town" than either of our current cars, where the IMA works optimally.

My best consumption figures in the C6 are often on my periodic Woodbridge-Cardiff run, where I can touch 40mpg. I can't explain why - perhaps its the fact I travel late evenings to avoid the traffic, or perhaps its cold air in the turbos, or just the geography/topology or just the very long period of stable cruise on the M4.

I have also noticed that C6 fuel consumption is very sensitive to different cruising speeds - the "sweet spot" for motorway cruising seems to be around 82 mph indicated - which equates to the French speed motorway speed limit of 130kmh, which is very close to the actual speed of the C6 at 82mph indicated - which seems to over-read my 1-2mph in my car's case. Coincidence?

Dropping to 66-70mph for the UK seems to offer a reasonable improvement, but the mid 70s seems to be sub-optimal.

Just my findings.
Sun Jun 05 2011, 07:59pm
Joined: May 31 2010
Member No: #135
Location: Essex
On a leisurely (60-ish mph) 90 mile motorway trip last Monday 48mpg in my 2.2 manual. Usually average around 36 mpg
Sun Jun 05 2011, 08:48pm
Joined: Nov 17 2009
Member No: #14
Location: London
drummond wrote ...

Why I ask, is that someone else has got 40mpg out of a 2.7, in conditions not so very different from mine. Does anyone have a 2.2 auto for comparison, or is there something I could do (or get done, more like!) to improve matters.

Not only that but I've experienced both extremes myself. I only ever look at consumption figures when I'm on long continental journeys. Usually on these journeys I have exactly the same compliment of passengers and luggage, usually I set the cruise control at exactly the same speed (I know cruise isn't necessarily the most fuel efficient mode but at least it is consistent), I usually drive the same autoroutes, I usually fill up at the same supermarkets, and in the same ambient temperatures I've seen results of between 32 mpg and 41 mpg between different holidays with no other variable I can think of.

I'm off again next month and with prices the way they are I hope my 6 is in one of its more parsimonious moods.
Sun Jun 05 2011, 11:58pm
Joined: Jan 22 2011
Member No: #350
Location: Paradera
I can't talk about long haul characteristics as our island only has city / country roads. But I noticed a sharp drop in usage by change of driving style other than accelerating less..
I got from 26 to 30 mpg (calculated from 10.9 to 9.5 l/100km) by the following trick: on accelerating I go 2-3 km/h over the speed I want and take my foot of the pedal for 1.5 to 2 seconds and then reapply to maintain the desired speed. This is best trained with the instantaneous consumption displayed. A friend told me about this trick, his Merc does the same and is supposed to be caused by turbo chargers remaining more active after acceleration and the deceleration shuts them down. Still have some hope the replacement of glow plugs I did this earlier this week will help me reduce consumption as I noticed cold engine consumption was a lot higher then once the engines reached normal temperature when driving (which is more than halfway on my home-work commute of 8 km). Glow plugs will mostly work for POST-heating in all circumstances.
Mon Jun 06 2011, 12:20am
Joined: Mar 08 2010
Member No: #65
Location: Northumberland
Before this thread gets too long, and believe me it will, I would like to share with you my thoughts on fuel consumption. Whilst I appreciate that fuel prices are at an all time high, I feel the sentiments expressed in the following will be shared by most members. This is a post I placed on the C5-L in Feb 2009, shortly before I switched to the C6, and as a response to a similar, seemingly interminable, debate on who got what consumption out of which model with which gearbox, (yawn):

OK, hands up all those who bought a C5 for it's fuel economy. Not many, I bet.
I bought my C5 3.0l Estate, and my previous C5 2.2 HDI Estate, because I love
Citroens. I bought them for the ride and the comfort and the styling and the
equipment and the capacity and the fact that they are not German. I bought them
for the same reason I bought an Xm Estate before that and a Bx before that.
Three large automatics and a GTi. I didn't buy any of them so that I could argue
over the last drop of petrol or squeezing the last mile out of a gallon. If I
was so concerned about fuel consumption I would have gone for a C1, or I would
drive my wife's C2.
I am about to trade up to a C6 3.0l petrol, pretty much for the reasons stated
above. I am not a wealthy man, far from it, but I don't go to the pub or gamble.
I spend my money on enjoying possibly the finest marque on the road. Driving
a big Citroen purely for the pleasure of it.


Mon Jun 06 2011, 08:45am
Joined: Sep 20 2010
Member No: #238
Location: Aldeburgh
Thank you one and all- I used to get around the "extra urban" figures on all my cars, but it seems like this is the exception. Ah, well.

Btw, Pete, apart from company cars and my wife's Mazda, every car that I've bought (and I'm 55) has been a Citroen. About 30 at the last count.....
Mon Jun 06 2011, 12:26pm

Joined: Apr 12 2010
Member No: #86
Location: Penwortham
verycleverman wrote ...
If I was so concerned about fuel consumption I would have gone for a C1, or I would
drive my wife's C2.

Having owned a 'facelift' 2.2 C5 Auto (with a 4 speed box) I find I actually get better consumption, with a 2.7 auto C6.

verycleverman wrote ...
I spend my money on enjoying possibly the finest marque on the road. Driving a big Citroen purely for the pleasure of it.


Couldn't have put it better myself, yes, we would all love to get 50, 60 or even 70 mpg, but if that's the issue, buy a Prius To be honest, I don't care to much about the milage, road tax, insurance or repair costs. You buy a car with your eyes wide open, nobody forces you to choose it. A great part of why people choose a C6 over say BMW, Jag or Merc is that they are different, and yes those 3 probably offer, better mpg. BUT!! would I want one, Not if it was free with a box of cornflakes.

The C6 is what each and everyone of chose to buy, love it or hate, WE picked it because it's different...........
Mon Jun 06 2011, 01:47pm
Joined: Apr 28 2010
Member No: #102
Location: Hampshire
I treat my MPG as a game that I play when i have time. I drive a lot on motorways and can do most of this out of the rush hour. If I am not at a rush I do sometime enjoy sqeezing every last mile out of every last gallon. My best so far in the c6 is 45 mpg . I did this by sitting on the inside lane of the m40 doing 56 mph for 100 miles . Not the most exciting drive but I enjoyed that challange. My C6 has manged 38 mpg over 2500 miles not bad for a big car. I also own a 3.0l Avantime best 36 mpg worst 14.1 mpg . A 320 Mercedes sl which returns 28-30 no matter how I drive and a 1976 Mercedes 350sl (v8) which does 14-20 mpg no matter how I drive. I love every minute of the drive and only really think if the MPG when I fill up .
Mon Jun 06 2011, 01:50pm
Joined: Nov 17 2009
Member No: #14
Location: London
verycleverman wrote ...
. If I
was so concerned about fuel consumption I would have gone for a C1, or I would
drive my wife's C2.

Pete, that's all fair enough and I agree. I did drive a 3.0 litre Alfa for seven years and espoused the same logic when the trip counter was frequently in the low teens. But my query is why does my C6 vary between low thirties and low forties? That's quite a variance, worse than 20% difference.

I know my C6 isn't a Fiat 500 TwinAir but if I could figure out what puts it in a humour to deliver 20% less cost to me I'd like to know.
Mon Jun 06 2011, 06:50pm
Joined: Sep 07 2010
Member No: #229
Location: Scotland
On a long drive home one weekend and on a very long straight, I tested mpg against the rear spoiler (yes, I was bored):
Took it to 78 on the cruise for about one mile = 33.1mpg, then took it 80 (to get the spoiler up) then dropped back to 78 on the cruise for about anoher mile = 32.1mpg. A saving of 1mpg (wow)
Although when taking Travlician's tip about taking it 2-3 mph above what you want then dropping back makes me wonder if it was the spoiler!

Oops, jst re-read the above and my reasoning it back-to-front! If deaccelerating a little improves mpg, my spoiler-up mode should have been higher than before.
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