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Highest MPG? (over 100+ miles)

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Sevenman   
Fri Dec 18 2015, 11:50am
Joined: Jul 05 2015
Member No: #2241
Location: Herefordshire
As I use my C6 for a lot of work driving and get a car / mileage allowance. I want to make sure I at least break even on HMRC mileage rates, which works out about 38 mpg for the 2+ litre category.

Below is a picture of the best mpg so far from the 2.7 C6 on a mixed Motorway/A/B road run.

It would be interesting to know what people have managed in the 2.7 (like mine), how much more the 2.2 can do, and whether the 3.0 is much different.

I think I will be able to beat the figures below in nicer summer weather and with less traffic.

I thought adding the 100+ miles requirement means it gets a good mix of conditions - I am sure I could get some very high mpg reading if I reset it coming down a long hill.

After 6 fills since I bought the car, it appears the computer over reads by a fairly substantial 8% when compared to a fuel used / miles driven calculation.

So the 47mpg below seems to be a real 43.5mpg.

Dan595   
Fri Dec 18 2015, 02:24pm
Joined: Nov 26 2010
Member No: #299
Location: Wiltshire
I've done around 840 miles on a full tank - 2.2 manual. This is unusual though - I typically get 710-750 miles. The trip computer underestimates consumption on mine - usual reading is 41.6-42.2 but measured consumption is 45+.

Not sure how many fills I have done since buying mine - seven years and 160,000 miles worth...
Sevenman   
Sat Dec 19 2015, 03:57am
Joined: Jul 05 2015
Member No: #2241
Location: Herefordshire
Dan595 wrote ...

I've done around 840 miles on a full tank - 2.2 manual. This is unusual though - I typically get 710-750 miles. The trip computer underestimates consumption on mine - usual reading is 41.6-42.2 but measured consumption is 45+.

Not sure how many fills I have done since buying mine - seven years and 160,000 miles worth...


840 miles on a track is impressive, and interesting that your computer underestimates mpg, a reverse of mine.

Probably only 250 fuel station visits or thereabouts... I like having cars with a long range so I can avoid having to go too often. Big tank and 1000 miles range would be nice, I think three are some cars that can just manage it.
drummond   
Mon Dec 21 2015, 10:34am
Joined: Sep 20 2010
Member No: #238
Location: Aldeburgh
I got 33mpg on my 2.2 auto, over 52000 miles. Mostly on motorways, cruise on at 75 (in this country) or 83 (France). Trip was accurate to within 5 miles/ tank.
DZR   
Mon Dec 21 2015, 12:45pm
Joined: May 19 2015
Member No: #2168
Location: Halmstad
Measured a bit over 5000 km, my 3.0 have managed to get an average of 44 miles/gallon. (in liter, 6,4/100km)

60% main/highway roads, 40% city driving.

Not bad, considering the car weighing almost 2 tons and rolling on 245`s
Tjensen   
Mon Dec 21 2015, 09:39pm
Joined: Jul 17 2012
Member No: #954
Location: Bergen
I have the same result as DZR on my 3,0 HDI. As low as 0,57 on a nice long trip, and more realistic an average of 0,65-0,67 (not much around-the-corner city driving)
Jarecki   
Sun Dec 27 2015, 08:46am
Joined: Feb 19 2015
Member No: #2069
Location: Poznan
What I read in this thread is a bit strange. Are You, gentlemen use the car for fuel saving? Are You know what the C6 is made for? I use it mostly for fun, so is quite hard to break 30MPG, but my average speed is around 70mph.
When the diesel is around 1GBP/l I'll think about... now (is 0,6)
Have nice driving!
Sevenman   
Sun Dec 27 2015, 10:22pm
Joined: Jul 05 2015
Member No: #2241
Location: Herefordshire
Jarecki wrote ...

What I read in this thread is a bit strange. Are You, gentlemen use the car for fuel saving? Are You know what the C6 is made for? I use it mostly for fun

Fun? I definitely didn't buy the C6 for fun. Comfortable cruising, and lots of work driving, but not fun. There is a TVR in the garage for fun, which is fairly close to the automotive opposite of a C6.



The TVR is managing about 24mpg as a long term average...
Eric   
Thu Dec 31 2015, 06:22pm
Joined: Mar 31 2011
Member No: #425
Location: Fareham
I averaged 42 mpg on a quick run from Munich to UK.
Sevenman   
Thu Dec 31 2015, 06:45pm
Joined: Jul 05 2015
Member No: #2241
Location: Herefordshire
Eric wrote ...

I averaged 42 mpg on a quick run from Munich to UK.

I guess by quick you mean Autobahn / Autoroute speeds rather than completed in 30 mins.

I would like to take the C6 to nice continental roads, but my wife's Mondeo is the newer car and has more luggage room
Tjensen   
Fri Jan 01 2016, 11:08am
Joined: Jul 17 2012
Member No: #954
Location: Bergen
The feeling of a C6 at very high speed : silence, control, comfort should be experienced. Difficult to imagine that a Mondeo experience can compare.
CitroenMan   
Fri Jan 01 2016, 04:07pm
Joined: Mar 13 2014
Member No: #1622
Location: Surrey
I average about 32.5 mpg, including my Italy trip! - About 455 miles per tank fill, aprox. 66 litres - However, I would be more impressed with your lowest MPG!!! Mines about 23mpg!
Eric   
Wed Jan 06 2016, 04:58pm
Joined: Mar 31 2011
Member No: #425
Location: Fareham
I can definitely recommend a 160KPH+ run in our C6s. The car is very happy at this end of the speed spectrum.... I have max'd mine at an indicated 245KPH on the Autobahns around Munich and it even made the Audi's and BMW's jump out of the way.... At 245KPH you are looking at 12MPG....!!!
1 User said Thank You to Eric for this Post :
 AndyPandyNI (31 March 2020)
Sevenman   
Sat Jul 08 2017, 07:12am
Joined: Jul 05 2015
Member No: #2241
Location: Herefordshire
I thought this thread needed an update as I have improved on my previous best with the 2.7 V6.

I was motivated by a colleague who has a £0 / year road tax Hyundai i30 and him telling me what mpg he was getting, so I set out to beat him. He got 74.2 mpg over 100+ miles so sadly the results below don't quite beat him. But in terms of improving over official manufacturer mpg figures, victory is mine.

This was a drive back from the north edge of London so included M25, M40, M42 and M5 as well as a bit of A-road.

My speed was steady. Tyres are new Goodyear Eagle F1 all round at the correct pressure (had just had the new valves set up). Gearbox had a flush last year, maybe that helps reduce drag.

Below are pics of the best mpg over 10+ miles and over 100+ miles, shame it dropped near the end.

I wasn't towed, and I didn't start on the top of a mountain (Mt. M25?).

I don't really think I can improve on this, and with the C6 for sale, I won't get the chance again.





3 User said Thank You to Sevenman for this Post :
 e3steve (08 July 2017) , Jas16 (08 July 2017) , 321dave (08 July 2017)
321dave   
Sat Jul 08 2017, 01:43pm
Joined: Sep 09 2011
Member No: #614
Location: Dublin
Hi Sevenman,
that's incredible MPG even for motorway driving! I never see anything remotely close to that. I was going to ask was it a 2.2hdi then I noticed you mentioned the 2.7hdi.

You mentioned the new tyres, but I'm guessing there must be more to the incredible MPG, something like the roads must be ever so slightly downhill and the road surfaces must be super smooth or very good. And you must be a regular user of good fuel. Has the 2.7 had the EGRs blanked and the engine chipped a little? Thanks as well for your contributions to the forum, every bit of help and information make the forum work very well and helps everyone to really understand the car to preserve them for the future.

Dave
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