Dreadful Fuel Consumption - 04 Diesel

[ATJS]

We recently purchased an '04 Rav to replace our 'R' reg petrol model which had provided brilliant service and was suitable for where we live - up a track on the edge of Dartmoor. Hence another Rav.'New' Rav has 86K on the clock - verified. A further motivation was that we'd grown weary and poorer given the average 25mpg returned by the old Rav, and research suggested that mixed driving should give us something approaching 40mpg. A month later and it's clear something serious is amiss - and I'm wondering why we bothered with the upgrade as we're still averaging 25ish mpg. It's possible the air mass meter was malfunctioning so we've replaced that. Performance may be a little better but I don't think it's made much difference to the fuel consumption. Driving style? Well - it's a mixture of country lanes and A and B roads. A fair proportion, maybe half, are short 'school run' type journeys of several miles with quite a bit of up and down. For myself, I'm certainly a 'gentler' driver than I used to be and even though the diesel engine is quite different to the petrol, even with the up hill / down hill element I don't have to push it so much. I'm quite easy on it. So, quite a lot of shortish runs on a cold engine but other easier stuff too. But 25mpg? Ideas anyone?

[152bobby]

I have a 2011 SR D Cat Auto Diesel and the mpg is shocking.

I struggle to get the mpg odometer to get above 28 mpg, which was more or less what I was getting in my Lexus RX.

Just NEVER believe the manufacturers figures, they are totally rubbish.

No doubt you will get some feed back asking about your driving style, whether the car is serviced regularly blah blah blah!!!

So if you want good mpg, buy a Yaris, obviously no use to you driving where you live.

[152bobby]

....also, short runs and cold engines in the same sentence as the word diesel is a killer for diesel cars.

You should have stuck with your beloved petrol.

[Heidfirst]

I have a 2011 SR D Cat Auto Diesel and the mpg is shocking.

I struggle to get the mpg odometer to get above 28 mpg, which was more or less what I was getting in my Lexus RX.

Just NEVER believe the manufacturers figures, they are totally rubbish.

No doubt you will get some feed back asking about your driving style, whether the car is serviced regularly blah blah blah!!!

So if you want good mpg, buy a Yaris, obviously no use to you driving where you live.

the D-CAT+Auto is a poor combination for mpg in any car - even in an Avensis you will likely only average ~36mpg (although yes, that is variable depending upon the nature of journeys & your style of driving).

The manufacturer's figures are fine as a tool for comparing different cars under the same laboratory conditions - of course that bears little resemblance to real world results. It's a disconnect that has been known for years but the gap between lab results & real world results has been growing with later vehicles - it can now often be over 20%.

& yes, 50% of his journeys being only a couple of miles is not what diesel is best at - it won't fully warm up. He can be thankful that he doesn't have a DPF on that engine!

[ATJS]

Hmmm.... The 'easiest' run I've done so far was not exceeding 70mph, clear motorway / dual carriageway for approx 140 miles; followed by as described. That tank averaged 32mpg. Still low I think.... So I'm now looking at my 176K miler battered and bruised petrol MOT failure (only small things but with a bit of a funny engine rattle - maybe £800 to set right) and thinking I've probbaly made a mistake. However, our '06 XC70 averages 39mpg although we tend to use that for longer runs. Still.... can't help thinking there must be something we can do? And, er, what's a DPF???? Do I want to know?!

[atkiman]

You should have done a good 40 mpg on that run. 32 mpg on mine equals130 kph on the autoroute fully loaded with a Roof Rack.

Find a good diesel injection specialist and have it checked, you could guess and change fuel filter , injectors all sorts and still not get it sorted,. On local stuff mine will do mid 30's.

Tony

[Heidfirst]

"And, er, what's a DPF???? Do I want to know?!"

Diesel Particulate Filter. An emission control device that accumulates & burns off soot in the exhaust but has a finite life & is usually ~£1000 to replace. It uses fuel to burn the soot so lowers mpg & also needs to achieve a certain temperature in order to do so - short urban trips don't let it & can lead to early clogging & hence replacement.

Based on what you have said earlier you absolutely do not want any diesel equipped with one (they became mandatory in 2009 in the EU but many diesel cars before that will have had 1 fitted already).