'04 V70 168 Geartronic 5 speed - realistic mpg?

[stimperley]

We have had the above spec V70 Sport for about 18 months now and, compared with some of the very impressive figures I have seen mentioned on here, I have always been slightly disappointed by its mpg. When I test drove it the computer was showing 41mpg average and I happily assumed this was the long term figure. However I now know that this can easily be achieved by resetting the computer and going for a leisurely motorway trundle. In reality, it was reading 39mpg when we picked it up a few days later and has continued to ever so gradually descend ever since. I thought that it had settled around the 36mpg mark a few months ago but now it is showing 33.1mpg. Its not been reset for several months.

Does anyone think this might be indicative of a problem?

Car has done nearly 140k, performs great - although I haven't driven another of the same spec to compare, been properly serviced twice by us (evidence of neglect before that though), I cleaned out the EGR plenum which was completely furred up but I am sceptical that this contributes much to general running. I did find that the air flow meter was also badly clogged. Sprayed lots of carb cleaner through it which cleaned the mesh completely & I think that cured the previously very smoky exhaust under load but, surprisingly, didn't notice performance improvement and mpg has continued to trickle downwards. I took great care with the afm but could the spray have damaged it, would there be other symptoms?

Admittedly the other factor is my good wife's inability to grasp the concept of driving economically and she does most of the mileage. She just plonks her foot on the loud pedal and leaves it there until at the last moment she has to hit the brakes ... Coupled with the gearbox's eagerness to perform - it is really quite difficult to keep it in top gear on local winding/hilly roads - I suspect this is a major factor, but she does do about 20 dual carraigeway miles a day too.

I suspect a manual gearbox would be a lot better for extracting higher mileages and I'm willing to accept that and the above are all it comes down to, but all thoughts/contributions gratefuly received.

Simon

[Jim314]

Deleted by poster. Thought this was a petrol. Too early in the AM here.

[stimperley]

I managed to completely fail to mention that it is a diesel, but think most UK owners would assume or realise that - or spot my signature! Would be more than happy with that figure from a petrol engine, especially as petrol is so much cheaper now. Our previous series V70 2.5 20V petrol did 26mpg!

I know MAFs can be fragile (which is what I cleaned, next to the airbox, not the throttle body). I also have an Alfa GTV V6 on which MAF failure is quite common but the symptom is also distinctive - flatspot around 3000-4000rpm. Does the same apply to the D5 anyone?

[stimperley]

Originally Posted by Jim314

Deleted by poster. Thought this was a petrol. Too early in the AM here.

No problem - thanks for your thoughts!

[gizze]

33mpg average is what I would expect to get from one of these.

I am looking for a V7 auto at the moment and would expect around 25 from a turbo petrol and 32/33 from a diesel.
I am currently in a Merc E320cdi estate with the later 7 speed auto and that has crept up to 35.5 average from around 33 when I got it, now at 105k and was at 60k when I got it.

I can get 40mpg sat at 75mph on the motorway, and can see 46mpg on a run sat on an A road doing 50-60mph, but that is not real world imho.


One of the most common reasons for a car to drink more is a faulty thermostat, is it reading correctly?
I know on the Mercs they should be sat at 90ºc within a few minutes and stay there, when they tend to stick at 80ºc people complain of massive drops in economy.


But I reckon if you are getting 41mpg on a run your car is fine.

[stimperley]

Thanks gizze. I think you are right about real world mpg - we do a lot of shortish journeys that end in a long drag up a steep hill home, which doesn't help. Its just the unrelenting, if gradual, downward trend of the average figure that is bugging me. Warm-up seems fine and temp ticks at centre of the dial but I'll keep an eye on it.

[Jim314]

I don't get the practice of leaving the computer average mpg to accumulate indefinitely. Of course, perhaps you don't want the hassle of recording these values at each fillup, but by not doing so you loose the resolution which allows one to see a trend developing.

It's much better to record the computer average mpg and mph at each fill to brim and then reset both. You ccould always use the individual values to recreate the overall computer average for imformation purposes and to compare this to the overall average from odometer and fuel pump readings.

If on some occasions you don't fill to brim, then don't reset the trip odo or computer average mpg and mph. Just record the amount of fuel added and when you do fill to brim add in that amount of fuel to get the total for that trip odo reading. Only then reset the trip odo and computer mpg and mph.

One thing you get from this is to see how mpg is correlated with average mph.

[stimperley]

Presumably the longer it is left between resets, the closer it is to a long term average - assuming it is accurate at all. Its never been such a concern that I have bothered to take readings and do the sums myself, its just that from what I had heard, I had expected it to be a bit better than it states. And it has never completely levelled off, just keeps on falling very slowly.

[NI_Volvo_Nut]

Mine is showing 38mpg, it does 55ish on a good run, drops to ave of 33 round town

[stimperley]

Originally Posted by NI_Volvo_Nut

Mine is showing 38mpg, it does 55ish on a good run, drops to ave of 33 round town

Is it an auto?