C5 HDI Heavy on fuel

[qprdude]

Yep, I use cruise control when I can get a couple of miles without roundabouts, and sometimes the speed limiter too.

[oneday]

speed limiter your just being a bit flash now us with the mk1 dont have that

[qprdude]

OOps, sorry, I had a Mark 1 but it was just a 1.8 lx I think. Had the little button to raise and lower the suspension, but not much else. Certainly not cruise control. Loved it all the same.

The Mk3 is the dogs B******s though, just oozes class and the comfort is pretty much unbeatable. They are getting cheaper all the time, especially the 2008 ones. I went for a particularly low mileage one as I intend it to be my last big car, so I paid a bit more.

[Citroenmad]

I have to say I dont find the 2.0HDi 110 C5 that economical, I think the body is too big and heavy for a relitively small amount of power. Keeping the car sat at 70-80 does seem to hammer the economy of the C5 110, which is why I find the 138 2.0HDi so much better.

However, your economy doesnt sound quite right. £50 to do 230 miles!

My Activa would do 230 for £50!

However ...

i use about 22 quid a week in fuel about 200 miles mostly cold running at this time of year price of fuel £137.9 ltr. all bought at the shell station if i use tesco or the likes of i use more and the engine runs rough so i keep away from them.

If that is correct that is about ... 56MPG?

[Peter.N.]

I know the 406 is fairly accurate as I can get over 1,000 miles from a tankful.

Using cruise control does not necessaraly improve consumption, on hills I let the car slow down a little rather than increase the throttle opening, just watch your instant read out and compare the mpg drop when you come to a hill and it opens the throttle.

Peter

[oneday]

chris last time i did the calculator it came out at 56.3 most of my trips are done to work and back twice a day thats 4 trips a day on quiet 30mph roads mostly one 2 mile stretch at 50mph and a little use at the weekend been doing this for the last 6 months and since i sorted the throttle slack and a few other things fitted cruise control it has always used more or less the same fuel' i do use millers all the time. and i do drive like an old fart {because i am lol}

[imperial21]

Well i am lost, by your answers i think some thing is wrong but i dont know where to look next, My eyes have started looking at replacement cars i am considering a Berlingo or 406 if i stay french or go for a passat !

[Peter.N.]

The 406 is a very nice car, it doesn't have the ride or space of the C5 but in all other respects its excellent, don't expect the sort of fuel consumption I get though, to drive as I do would bore most people to tears, but with normal driving as long as you don't do all short journeys with you foot to the floor you should get around 50 mpg.

Peter

[DickieG]

The fuel computer in my C5 gives a different calculation to using the traditional method of monitoring full tank to full tank to miles shown on the speedo as the computer shows 2mpg under @ 41.4 mpg (over 2,500 miles) compared with 43.5 mpg and that's in day to day running around/commuting which isn't bad considering the amount of grunt available upon a light squeeze of the accelerator.

[imperial21]

Is there anyway of testing the air flow meter ? As i think the car was better on the previous airflow meter ! I have double checked the part numbers on old and new units.

[myglaren]

There are a few test guides on YouTube.

[Citroenmad]

Check that the MAF is genuine Citroen and not an aftermarket, make sure that it is clean also.

Check that there are no induction leaks and that the air filter is clean. Check the intercooler for leaks at the bottom.

I've had all of the above on a 110 C5 and each one effected economy.

[bobins]

The fuel computer in my C5 gives a different calculation to using the traditional method of monitoring full tank to full tank to miles shown on the speedo as the computer shows 2mpg under @ 41.4 mpg (over 2,500 miles) compared with 43.5 mpg and that's in day to day running around/commuting which isn't bad considering the amount of grunt available upon a light squeeze of the accelerator.

I know my C5(X7) has the option in Diagbox to turn on or off the (effectively mask or not mask) the fact that it uses more fuel during its DPF regeneration cycle but doesn't show it. I think the default is set to mask the higher fuel use, so it's using more fuel than the on board fuel calculation is telling you.

[imperial21]

I know there is a clip missing from one of the pipes past the maf but i didnt think it would matter, The maf is a Genuine VDO cost me plenty !!! Airfilter is from june / july and is ok
When i first got the car i did a trip and it was alot better on fuel, If i remeber rightly, I have been thinking that i will fit cruse control to the car to make it a cruser.

[myglaren]

Mine is a bit thirsty, as was the previous C5, normally 32 mpg. Driver to blame, short trips and lead boots.

For the past couple of weeks my son has been using it a lot until he gets his bike back on the road and the fuel consumption appeared to have increased rather dramatically, low fuel warning at 385 miles where it usually pops up at about 430, which leaves enough in for 2-3 days before filling it up again.

Filled it up at the local Shell station without bothering to look at the gauges and the guy asked for £76.88 which came as a big surprise
I was expecting it to be in the region of £90 as the odometer had a further 60 miles on it.
It looks as though the fuel sender is out of whack. On refuelling - I always wait for the low fuel warning to pop up and then brim the tank - I have found that there is progressively more left in the tank than the previous fill up if I head straight for the filling station.
Probably time (when the weather is better) to hoik the pump/sender unit out and check it over.

This fill-up gives a calculated mpg of 36.24, much better than previous figures where long motorway journeys are not involved.
Long trips give >60mpg.