High Diesel Consumption On My 2.0 Hdi C5

[juls]

Can any one help me as I Have a diesel 2.0 HDI C5 and I am only getting average 42 MPG this is driving on a Motaway at about 65 MPH around town its only about 30 MPG. The engine runs OK and drives fine I can not understand why.

[old'uns]

42 not too bad, i get this with mixed driving, estate with weight of approx 2 adults always onboard and 160k on clock.

doubt i'd get much more even at constant 65mph?

generally get 550 miles on tank =42ish

to get 45 you'll need to do 600 ish, 50 about 650+ miles ?

the C5 in any form isn't exactly lightweight & 110bhp won't set the tarmac on fire

[Johndouglas]

I have in the past driven on a motorway with the cruise set at 55mph and 35 miles later acheived 60mpg on the computer. But my average mpg is more or less inline with yours. On two recent trips from London to Malaga I recorded a 45mpg and a 42.7mpg (but with a well-loaded estate car)

[juls]

42 not too bad, i get this with mixed driving, estate with weight of approx 2 adults always onboard and 160k on clock.

doubt i'd get much more even at constant 65mph?

generally get 550 miles on tank =42ish

to get 45 you'll need to do 600 ish, 50 about 650+ miles ?

the C5 in any form isn't exactly lightweight & 110bhp won't set the tarmac on fire

Thanks makes me feel alot better as your right it is not the lightest of cars as you say

[juls]

I have in the past driven on a motorway with the cruise set at 55mph and 35 miles later acheived 60mpg on the computer. But my average mpg is more or less inline with yours. On two recent trips from London to Malaga I recorded a 45mpg and a 42.7mpg (but with a well-loaded estate car)

Thank you I will do a more controlled test as you have and let you know

[Randombloke]

Best I've ever had with a 5 speed 2.2 is about 46 mpg. This is cruising with no roof racks at about 67 (just below the 110 kph where the H3+ changes the car setting angle for extra down force=extra drag). Otherwise at 70 to 80 mph with no roof racks 42 to 44 mpg.

 

2 hang gliders on roof rack at 80 mph=29 mpg!

 

I'm told the six speed 2.0 pre DPF is the most economical Diesel C5.

 

I set the distance to travel to 1,000 km in the trip computer, this is about 620 miles and is a reasonable target, being about 44 mpg. If I have no Sat Nav destination set I can see how close I am to that 44-ish mpg goal.

[Guest Chilie]

Wow 42 - If only I was getting 42 I would be a happy chappie.

 

My 2.2HDI was until recently doing 31!

 

I have now had the DPF filter replaced and sorted out the back brakes that were binding and its up to 35 MPG. Im still thinking i have a problem somewhere but as yet I havent found it.

 

If anyone has any ideas where I can look next I would be grateful.

[72dudes]

Wow 42 - If only I was getting 42 I would be a happy chappie.

 

My 2.2HDI was until recently doing 31!

 

I have now had the DPF filter replaced and sorted out the back brakes that were binding and its up to 35 MPG. Im still thinking i have a problem somewhere but as yet I havent found it.

 

If anyone has any ideas where I can look next I would be grateful.

 

Well, just to add to the discussion, my 2.2 HDi manual has averaged 44.5 over the last 15k miles so I'm very pleased. I cruise on motorways at around 75 MPH or 2500 RPM (the 2.2 has higher gearing than the 2.0, which I like). This is done brim to brim, not just relying on the computer.

 

However, the recent cold snap and the high winds can affect consumption. Last tankful gave me 42.0 even after a 200 mile journey. Tyre pressures can also affect mpg so check these regularly. Other obvious thing is air filter, but driving style counts for such a lot too, I'm a member of IAM (Advanced Motorists) so I tend to plan ahead, use right gear, feather throttle etc, and I usually get very close to government combined mpg figure on whatever car I've owned (apart from my wife's Rover 216 auto which is bl**dy hopeless on fuel!)

 

Edit: My C5 2.2HDi:

Worst tankful - 39.8 MPG

Best tankful - 50.7 MPG (warm summer day, no wind, light traffic, long journeys etc)

[72dudes]

Best I've ever had with a 5 speed 2.2 is about 46 mpg. This is cruising with no roof racks at about 67 (just below the 110 kph where the H3+ changes the car setting angle for extra down force=extra drag).

 

Are you sure about this randombloke? I thought the idea of the front dropping down at 110kph was to reduce wind resistance, therefore drag, therefore helping decrease fuel consumption??

 

If what you say is correct, what's the thinking behind it?

[Randombloke]

Are you sure about this randombloke? I thought the idea of the front dropping down at 110kph was to reduce wind resistance, therefore drag, therefore helping decrease fuel consumption??

 

If what you say is correct, what's the thinking behind it?

 

I read that the H3+ drops the suspension 11mm at the rear, and 16 mm at the front above 110km/h to aid stability, which it does by creating more down force. It's the difference in drop between front and rear that makes the car act like a flat plate at an angle to the air stream, creating negative lift or down force. That extra down force will cause extra drag. If you now put a 20 ft HG on top of the car, you can see the drop in fuel economy by using the cruise control and setting 104/106/108/110/112/114 km/h in steps on a long run down to the Alps on the flatter sections of the French countryside. It's surprising how little over 110 you need to go to see the economy plummeting from about 7.5-7.7l/100km to well over 8 with an increase of some 5 to 10 km/h.

 

I found that there is a "sweet spot" at about 67 mph, which I wondered about until I worked out that 67 mph=110km/h, roughly!

 

If you have an H3+ car, try running it close to either side of this changeover mark. You'll see a jump in fuel consumption. It's not as bad as it gets with 2 hang gliders on the roof, but I think you'll see it.

[72dudes]

I found that there is a "sweet spot" at about 67 mph, which I wondered about until I worked out that 67 mph=110km/h, roughly!

 

If you have an H3+ car, try running it close to either side of this changeover mark. You'll see a jump in fuel consumption. It's not as bad as it gets with 2 hang gliders on the roof, but I think you'll see it.

 

Interesting, I'll try the thing with the cruise control.

[old'uns]

don't all C5's drop above a certain speed anyway?

[Guest Terry Toye]

Well, just to add to the discussion, my 2.2 HDi manual has averaged 44.5 over the last 15k miles so I'm very pleased. I cruise on motorways at around 75 MPH or 2500 RPM (the 2.2 has higher gearing than the 2.0, which I like). This is done brim to brim, not just relying on the computer.

 

Edit: My C5 2.2HDi:

Worst tankful - 39.8 MPG

Best tankful - 50.7 MPG (warm summer day, no wind, light traffic, long journeys etc)

Hi,

I have the 2006 2.0 HDI 138 bhp Euro IV FAP 6 speed Auto Exclusive estate.

Have had it since last Sept.

I travel a 55m round trip each day to work. (Has about 30K on the clock now).

My average over the last 6,500m is 37.6 mpg real (ie total fuel in to miles travelled. I'm an Engineer and I like to be accurate).

HOWEVER the trip meter shows average speed 30mph for this period and 42.7mpg

SO THE FUEL METERING LIES. It's 12% inaccurate.

This will also mean it will tell you that you have 12% more miles left than you have.

 

If you look at Citroen's (government) figure for 'Combined' fuel consumption (39.8), then the mpg I'm getting is just about right.

With the 6 speed manual box they say you'll get 46mpg - I believe them.

WHOEVER was the pratt who designed this new high-tech Autobox which is 15% less efficient than the equivalent manual.

Moan moan.

 

All the best,

Terry Toye

[Johndouglas]

SO THE FUEL METERING LIES. It's 12% inaccurate.

 

Not so on my C5. Mine has same engine as yours but with six speed box. I too like to keep accurate consumption figures and several times I've done the 1300 mile run from Malaga to London. At first I noted down the number of litres taken on at each fuel stop and then at journey's end, divided litres into miles. I quickly realized that my calculations agreed almost exactly with the computer. As did the distances agree with Microsoft Autoroute programme. The last few runs have given me averages of 46mpg, 43mpg, 42mpg and 27.5mpg. The last figure is low because of caravan towing, and the other variations are speed and load related.

[DaveHerns]

Not so on my C5. Mine has same engine as yours but with six speed box. I too like to keep accurate consumption figures and several times I've done the 1300 mile run from Malaga to London. At first I noted down the number of litres taken on at each fuel stop and then at journey's end, divided litres into miles. I quickly realized that my calculations agreed almost exactly with the computer. As did the distances agree with Microsoft Autoroute programme. The last few runs have given me averages of 46mpg, 43mpg, 42mpg and 27.5mpg. The last figure is low because of caravan towing, and the other variations are speed and load related.

Hi

 

I also have the 2006 2.0 Hdi 6 speed manual. My MPG is nothing to get excited about but I'm doing a test using Esso/ Shell fuel instead of Sainsbury's and I think it's improving

 

At 27K miles my air filter is dirty and I think it doesn't get changed to 60K - especillay being a lease car. I may treat it to a new filter . It looks the same as the filter in my old Peugeot 406 Hdi but i believe it's a different part no. with a higher price

[Stuart js]

Hi all,

I drive my 2.2hdi '03 auto, lightly, I get on a run, 125 miles straight off, full tank, according to the trip computer, 44-46 mpg at just under 70 mph, but if I do the same journey at 75-80 mph then it drops to 39-42 mpg. I think this is good for a car that is not exactly a lightweight. However, if you drive in town it does drop to mid the twenties.

To put it into context, I have friends who drive smaller cars and not many can beat 45 mpg.

 

TTFN

Stu.

 

Question, what is a DPF filter?

 

.

[Guest Chilie]

Question, what is a DPF filter?

 

.

 

Diesel Particulate Filter - its part of the exhaust system and traps the black soot that you otherwise see from diesel engines especially under hard acceleration. Oh and its costs a flipping fortune to replace! My next car definately will not come with one of these.

[Randombloke]

Oh and its costs a flipping fortune to replace! My next car definately will not come with one of these.

 

You'll have to buy an older diesel then, and with the higher CO2 emissions the road fund tax will cost more. Looks like all diesels sold will soon have DPF to comply with the relevant legislation.

 

I drive my 2.2hdi '03 auto, lightly, I get on a run, 125 miles straight off, full tank, according to the trip computer, 44-46 mpg at just under 70 mph, but if I do the same journey at 75-80 mph then it drops to 39-42 mpg. I think this is good for a car that is not exactly a lightweight.

 

This is pretty good for a 2.2 auto. You're a careful driver. I get about 42mpg at 80 mph, but my 5 speed manual seems to do slightly better in France than in the UK. Probably longer journeys and fewer stops.....

 

My friend with the 02 2.2 auto is getting just over 40 on trips with similar speeds.

[Guest Chilie]

You'll have to buy an older diesel then, and with the higher CO2 emissions the road fund tax will cost more. Looks like all diesels sold will soon have DPF to comply with the relevant legislation.

 

My friend with the 02 2.2 auto is getting just over 40 on trips with similar speeds.

 

Im sure your right about the DPF and pressure to reduce emissions etc but im simply going to go back to petrol when I change my car again. I cant make diesel pay - im getting similar economy to my previous 1.8 petrol picasso and the fuel is more expensive so it doesent make sens with the type of driving im doing. I dont drive the car hard very often but I spend a lot of time in stop start traffic and its killing the economy I may as well have the petrol performance as im not saving any money with a diesel.

[72dudes]

Interesting, I'll try the thing with the cruise control.

 

Randombloke - it's been too windy to try this and I struggled to find a stretch of road flat and empty enough anyway.

 

But I did notice one interesting thing: travelling at a steady 67 MPH on cruise control with the computer reading "instantaneous consumption", I pressed the Sport button. The consumption increased from low 50's to high 40's. Tried it twice more and both times it appeared to use more fuel in Sport than in normal mode.

 

Have you tried this? Is there an explanation - e.g. does suspension drop slightly when in Sport mode, or was it just pure coincidence?

 

Cheers.

[Jonno]

Randombloke - it's been too windy to try this and I struggled to find a stretch of road flat and empty enough anyway.

 

But I did notice one interesting thing: travelling at a steady 67 MPH on cruise control with the computer reading "instantaneous consumption", I pressed the Sport button. The consumption increased from low 50's to high 40's. Tried it twice more and both times it appeared to use more fuel in Sport than in normal mode.

 

Have you tried this? Is there an explanation - e.g. does suspension drop slightly when in Sport mode, or was it just pure coincidence?

 

Cheers.

 

I have a work colleague that has a C5 Exclusive (or is it excecutive?) its a 2.2HDi, when he puts it into sport mode the suspension does seem to drop slightly.

 

Is it true that its only the 2.2HDi's that have the "eolys" fluid additive to help clean the DPF filter. Yes it is an expensive job to have them done. My daughter was quoted around £900 to have the DPF filter changed and a recharge of the aditive on her Pug 307 HDi (fortunately done under a warranty)

I had the 'cat' changed on my Xsara 2.0HDi for £141

[Randombloke]

I have a work colleague that has a C5 Exclusive (or is it excecutive?) its a 2.2HDi, when he puts it into sport mode the suspension does seem to drop slightly.

 

Yes, 16mm at the front and 11m at the rear. All H3+ C5s are in "Sport" mode above 110 km/h, AIUI.

 

Is it true that its only the 2.2HDi's that have the "eolys" fluid additive to help clean the DPF filter. Yes it is an expensive job to have them done. My daughter was quoted around £900 to have the DPF filter changed and a recharge of the additive on her Pug 307 HDi (fortunately done under a warranty)

 

I have placed the costs of DPF + Eolys replacement on the list before. My indy wanted £142+VAT for the DPF, and £77+VAT for fluid.

 

Only 2.2 HDi MK1s have the DPF plus fluid, but later C5s have it on the other engine sizes as well. Have you ever been to Rio de Janeiro or Lagos? Have you ever seen the amount of soot that comes from Montego Perkins diesels or older XUD lumps? Compare it with the new diesels! Let's not kill off the environment too quickly......

 

But I did notice one interesting thing: travelling at a steady 67 MPH on cruise control with the computer reading "instantaneous consumption", I pressed the Sport button. The consumption increased from low 50's to high 40's. Tried it twice more and both times it appeared to use more fuel in Sport than in normal mode.

 

Have you tried this? Is there an explanation - e.g. does suspension drop slightly when in Sport mode, or was it just pure coincidence?

 

Below 110 km/h you have a choice between Sport and Normal mode, set on your centre console. At 110 km/h, IF the road is smooth enough, the H3+ C5 goes over to Sport mode automatically as I understand it. The light won't come on, but you are now in Sport mode. Drop dimensions for Sport mode above.

 

Anyway, you have now seen why I keep talking BS about the 67 mph sweet spot. Set cruise so that the needle is a hair's breadth below the bottom of 7 on the 70 mark on your speedo... fuel is now £1.12 where I live..... :unsure:

 

2002 2.2 HDi Exclusive 5 speed did 45.6 mpg early this week on a return trip to Southampton (including town driving) from Kent despite the winds, courtesy of this technique.

[cardsharc]

Wow 42 - If only I was getting 42 I would be a happy chappie.

 

My 2.2HDI was until recently doing 31!

 

I have now had the DPF filter replaced and sorted out the back brakes that were binding and its up to 35 MPG. Im still thinking i have a problem somewhere but as yet I havent found it.

 

If anyone has any ideas where I can look next I would be grateful.

try using a bottle of diesel treatment in the tank

[myglaren]

My consumption has been absolutely dire, around 32MPG but I rarely go anywhere but work and shopping. Work is four miles and the shops only 1 mile. Not ideal by a long shot.

 

However I have just returned from a 620 mile journey. Filled the tank prior to setting off (Sainsbury's) and there is still around 1/8 tank left.

Mainly motorway driving (M1/A1) with a few five-mile-an-hour creeping along for miles stretches. About 100 miles city driving around Bedford/Milton Keynes, Nottingham and Lincoln.

 

Approximation gives me 56 MPG.

[Randombloke]

Approximation gives me 56 MPG.

 

Excellent! I too have found the C5 does not reward town or short distance driving, but is excellent for its size on long trips.

 

Must cycle into town more, the council in Maidstone will help motivate me with the parking from hell. I must thank them for their unstinting attempts to improve my health.

 

Incidentally, my target for every tank in my C5 is a minimum of 621 miles or 1,000km. If I run down to the last 6 litres in the tank then that's about 42.8 mpg.