Poor Fuel Consumtion

[Crystalcat]

Hi Guys & Gals,

I've just bought my first Rav 4 - 2.2 XTR D Cat Auto & im a little disappointed to say the least with the fuel consumption i'm getting.

I only go short distances but seem to be only getting 22 mpg. Either worked out manually or via the OBC.

Has anyone else suffered lower fuel consumption? Would love to hear anyone elses thoughts or ideas.

Crystalcat

[cabcurtains]

How short is short?

[Crystalcat]

Only 2/3 miles to work & back and to supermarket etc.

Had a golf 2l fsi petrol before and got 28 - 30 doing the same sort of trips

[cabcurtains]

With the weather as it is the car wont be getting anywhere near warm, so it will be running on choke albeit automatic not the type you used to pull out. As the weather improves it will get better but Diesel and 2-3 mile journeys are not the best combination.

Also the car has a D-Cat DPF system for emissions reduction which will uses fuel to burn off soot, this wont help.

[jedi134]

Autos always return poor mpg in city center use

And the golf will be a lighter car, was this auto and triptronic?.....

[Crystalcat]

Golf was manual but still 2.L my husband has a merc Vito that is auto 150 bhp and that returns 28 short trips 35+ on a long run my brother in law has a ford kuga that only goes on short runs and that is doing 34 mpg had a freelander sd4 HSE on demo and that driven hard returned 29 mpg and that was 190 bhp

[cabcurtains]

There are far to many variables in naming all the other cars, do they do exactly the same journeys in the same weather?

The golf comparison is more fair as you owned the car, as Jedi said its lighter, also it was a manual.

Wait until it warms up and see what happens to the figures, you could take it to Mr T and ask them if it needs an ECU update, but assuming you bought it from a main dealer it should have been done.

Honestly on a 2-3 mile drive the MPG looks normal not great but ok, my Avensis doesnt do much more if i reset the trip and drive a couple of miles from cold.

[Daveyonthemove]

The MPG will suffer on a diesel car if is not taken on a long run.

Diesel engines need to be hot to run at their optimum, and a short journey like that will barely raise the water temp on the dash.

Then there is the DPF. It will be working overtime if you are only doing short runs as it won't be getting up to temp to burn off the carbon, so the 5th injector will be throwing fuel onto the DPF in order to clean it before it gets clogged up.

A diesel engine is useless for anyone who is not doing 12k miles or more a year, and at least one long run on a regular basis.

I doubt your MPG will improve much as the weather warms up, and I seriously think you need to take it on a good run sometime soon before the DPF does clog up and you land yourself a big bill for a replacement.

Sorry if that seems a little negative.

[Jozsef]

Hi Janet,

Add some BG244 or Wynns' Formula Gold Diesel Treatment to your diesel. Visit your grandma who live in rural areas and calculate the consumption manually. The mpg info on board sometimes gives you false info. 6-7 mpg improvement in consumption and your gradma will be happy.... You'll be happy as well.

Jozsef

[Hoovie]

Hi,

Not many of us 150BHP D-Cat Auto owners around on the forum yet I think :)

Got some questions which hopefully someone may be able to answer? :)

QUESTION #1: I understand that you only start to get the optimum MPG once the engine has run it and that takes a certain mileage. Some makes quote 3k miles, some 5k, some seem to quote 10k before this happens. Anyone know what the 'run in' mileage for the 2.2D is?

Mine is now over 12K so I am assuming mine is fully run in. What is the current mileage of your XT-R?

As has been said, the economy is significantly worse when the engine is cold. Also, it is said that economy is worse at this time of year due to the cold temperatures.

QUESTION #2: Does the cold external temperature affect the engine performance once the engine itself is up to temp? I know in the 'old days' you might block off some of the rad with cardboard to stop it cooling too much but I guess things are more advanced nowadays? :) . Is the worse economy in winter (once engine up to temp) now more due to factors of extra loading such as lights, seat heaters, wipers etc, that would get used more in winter then summer? Anyone know|?

A major factor of Economy is having the right Tyre Pressure.

I have on my RAV4 SR - and also on my previous RAV4 2005 model - a TPMS System that gives me accurate PSI and Temperature of the tyres, and have noted that once the ambient temp gets below about 5-8C, the Tyre Pressures can drop significantly as the temperature drops and this could have a significant effect on economy. Plus on a 2-3 mile journey, the tyres will hardly have had a chance to warm up (prob 2C max higher).

Have you checked your PSIs are still good for your normal journeys?

Now ...the "Combined Average" for your car is meant to be 39.8mpg - for mine, it is 39.2mpg so I guess that is the "Target"?

I have been wondering about the economy of mine a little actually, and - liking statistics and numbers - made a few notes during my weekend driving regarding the economy achieved related to the style of driving, which may be of interest to compare once you get a chance to do a some longer runs?

(this is the very boring bit coming up!)

FWIW, this is what I got in the last few days ... oh, and I also have noticed that - on my RAV4 anyway - the trip computer/mpg readout is nigh on spot on (if anything, very slightly errs on the pessimistic side) so for a change, I actually believe what it tells me!

From Friday to Saturday, driving the majority on motorway at around legal limit, plus country roads and a little bit of rural roads, I averaged 33.3mpg over 503 miles

After I filled up on Saturday, I tried a test and between Amesbury and the Reading Services, I kept to a steady 62MPH and recorded 38mpg on the computer

Filling again on Sunday, the overall economy between fillups on the Saturday and Sunday was 31.9mpg over 180 miles, but this included a fair bit of town driving in Reading, which will hurt a lot, of course.

the on-board computer registered the MPG as around 1mpg lower then the brim-to-brim calculations, btw.

On Sunday, the first 150 miles were done at 31.7mpg (mostly Motorway at around 65-70), and as another little test, reset the computer when I got to a 50mpg Average Limit roadwork section for 10 miles, followed by a 10 mile 70MPG camera section and those 20 miles averaged 36.3mpg.

After a break, reset the computer again and the last 100 miles of the day were at an average of 35.5mpg, driving around 60MPH on single carriageway country roads in the main with the odd village.

Overall average for the weekend is around 33mpg over about 1,000 miles.

All the above was done in cold ambient temps and with Winter Tyres on (they can have a 2-3mpg effect on economy I understand?).

All fuel used is Shell V-Power Diesel

Cruise Control used extensively

So the conclusions for my own 2.2D-Cat Auto is that I don't stand a cat in hells chance of getting 39.2mpg, at least in the current conditions.

I should say that I never seem to get the kind of mileage others seem to achieve (lead foot I guess!) so others owners should expect to better my numbers

HTH (if only to help insomniacs! )

[Guest]

And he doesn't stop for a cuppa on that entire journey, I had it stewing in the pot all day

Gus

[Crystalcat]

Well guys what a lot to digest but very interesting as your average is still 50% greater than mine.

My rav is 15 months old and has done 12k miles so should be run in and is an ex Toyota uk car.

I would be happy with low 30's at the mo.

Anyway as we speak it's back at mr t's for them to do some tests as at least they agree it should do more even on short runs.

So watch this space.

It should be back by the weekend, when we are going on a run, so I'll see what happens to the mpg then. I'm also going to try vpower diesel to see if that helps too.

Bye for now.

[Hoovie]

I am nipping into the local town tomorrow morning to pick up a parcel - it's about 3 miles each way. I'll try to remember to reset my MPG display and see what that short journey shows me economy wise and let you know :)

[Crystalcat]

Thanks - i'll be interested to see what mpg you get.

[Hoovie]

Right. Did my little test this morning ....

Reset display and drove exactly 4 miles to Sorting Office - only delays was a little traffic going through small town. Drove fairly gently as engine still cold of course.

I got 29.5mpg after the 4 miles. Ext Temp was 8c, water coolant display by that time had started to move off the initial horizontal bar, so not at full operating temp yet.

by the time I got home, still 8c outside but coolant up to normal position and overall MPG showed as 30.3mpg on the total 8 mile trip

So on my little test, It sounds like your 22mpg is a fair bit below what to expect? But bear in mind I had nearly totally clear roads,so little braking and acceleration going on - YMMV (literally!!)

I suppose if you are doing this 2-3 mile journey 10 times a week, you are never letting the car get up to full temp and things are getting clogged up and could be a good reason for your poor economy, going by the comments and observations made already, so maybe need to go for a bit of a 'blast' at the weekends? :)

[Tech01]

How long do diesels take to run in? Much longer than 3k to 12k miles!

A brand new diesel engine can be unbelievably stiff, and reluctant to deliver power. It should be treated fairly gently for the first 50 miles or so, and then you can begin. Avoid labouring in low gears, and also avoid cruising at steady speeds - diesels are best run in by "mixed motoring". If you must do a motorway run in the first 200-500 miles, then vary the speed every five minutes or so, or even less. 70mph won't do it any harm, but not for extended periods. This all applies for the first couple of thousand miles.

Diesels prefer to be run in by hearty acceleration: use all the power available, and don't be afraid to open the throttle wide. Conditioning the cylinder bores is made worse by tiddling about.

Diesels run in, then they run in, and then really run in. The engine won't be at its free-est and at its best until it's got 25-30,000 miles on the clock.

Chris

[cabcurtains]

I'm still sticking to my original view, if the Hoovemesiter has been queuing then it would have been even worse, and 8c is pretty tropical compared with the last few weeks.

[Hoovie]

I'm still sticking to my original view, if the Hoovemesiter has been queuing then it would have been even worse, and 8c is pretty tropical compared with the last few weeks.

I got up to 30.5mpg as I entered town and it dropped to 29 as I left town 20 seconds later due to traffic, so if a 2 mile commute was in a town environment .....

I'll repeat my test next time I am starting a cold engine and in a busy environment (Sometimes I think I live in one of those car adverts where the roads are empty except for yourself! )

[Andy Pigott]

Janet,

We bought a 2.2 diesel last year and I am not overly impressed with the mpg on short journeys. Longer is less of a problem but around town we are in the low to mid 20"s.

How did yor get on with your Mr T chat?

Andy

Ps. Love the car in every other way....

[Crystalcat]

Hi Andy,

At last someone else who is having a similar issue with the fuel consumption.

As to Mr T - basically they checked the usual things like injectors, valves etc & found them all to be perfectly fine - surprise surprise!

I've now to brim the tank full of fuel, reset the average mileage & go on a long journey which i am doing this weekend, so all i can say is i'll keep you posted. If the MPG is still low they want to drive it for a few days to see what they get. Think this issue has a way to go yet.

I agree tho I love the car except for the MPG issue.

Janet

Crystalcat

[Whiteclaw]

I find it can depend where you get your fuel.

I am getting god awful results if I put in £30 at Sainsbury, but if I go to Morrisons, at the same price and amount, I get far more. I suspect some supermarkets really are selling crap.

[Gods_gift]

I go from Newcastle to Reading regular for work which is about 312 miles and my trip mpg reads 42 mpg on tesco diesel 56 plate xt4 99k miles

[bothwell_buyer]

I thought the whole issue of soot was that it doesn't burn - its the result of burning? So why push the stuff back through the engine again? I read ancs note that by doing so does something to nox but I wonder at the sensibility of putting soot through an engine - after all its just carbon is it not? I know you oil-burning nerds will try to convince me otherwise but I can't be fooled - I got my O-level Chemistry at school only 45 years ago. Theres more soot comes out of a steam engine so why did they never re-circulate it if its so beneficial?

No wonder yer only getting 22mpg! Crumbs... number 2 RAV gets that being driven hard with the turbo spinning and the engine revving at 4000rpm. But then I pay less for the VPower petrol. You must be utterly sick paying so much for diesel then getting tractor performance and problems to match (well if you read the topics on here most are related to burning-diesel type cars.

Good luck.

[Gods_gift]

Are you getting a lot of black smoke when you put your foot down?

[Crystalcat]

Don't think so but don't drive it hard.

Hubby driving on the long run later (he has a heavier right foot than me) - ill let you know what mpg I get Sunday night