[Closed] Poor fuel economy from a diesel - does this sound right to you?

I have a Magane Grand scenic with the 1.9dci engine.

I do most of my driving aroudn town and get less than 40mpg - I can get this up to 45-50 on mixed roads if I'm *really* careful with my right foot and drive for economy.

I think it's not bad for a heavy car with a turbo engine, tbh - I used to struggle to get the right side of 30 on my Old School Saab 900 2.0 Turbo...

40 mpg is indeed poor.

You could look at your driving style. You need to get up to speed with middling acceleration and then hold as constant a speed as you can, then lifting off well before any traffic lights or roundabouts and coasting in. If you want to do even better lift off at every opportunity and just touch the throttle reeally gently so that you slow down very slowly. This can annoy drivers behind you though if you take the piss.

You don't have to be slow in acceleration, but you do have to be really smooth and have a light touch, and use the accelerator and brake as little as possible once up to speed.

Some people don't realise how they drive - I had a lift with a bloke who was always hard on all the pedals, regardless. Boot down, brake hard ALL THE TIME even on the motorway at overall perfectly reasonable speeds - he thought his driving was perfectly normal, I was almost sick in the passenger seat.

Also check tyre pressures.

Drive a 2litre Volvo V50 RDesign Diesel.

Consistently get between 50-55mpg combined - obviously bit more if a doing a long motorway drive.

Make of that what you will.

<edit> but then of course it is a Volvo so can't have it all ways 😉

42 doesn't sound unreasonable for urban driving, its about what we get from a VW 140bhp diesel.

one thing that is recommended with Renault Diesels is to really boot them every now and again - somethign to do with the emissions control stuff getting sooted up if you don't get a bit of pressure going through the turbo and engine.

The suggested advice is that as a rule of thumb, take the stated economy figures and multiply by 75% to get to real world numbers.

Changing your car for the sake of 8mpg? A complete waste of time and money.

Blimey! my 140bhp VW does 50-55 urban/combined and 60 moterway and i'm not very timid!

42mpg is the best I can manage in 'driving Miss Daisy' mode. If I had my own way with the right pedal i'd be getting around 34mpg.. which is rubbish.

Im peeved as my 12 year old Golf estate Tdi (90bhp)was thrashed every day and never fell below 47mpg

If you are not doing many miles then it will automatically be poorer than 'average', and there is nothing like a modern TD for having a variation in mpg it seems.

And it is showing an Urban of 30mpg...

so your golf produce 40% less power and used 15% less fuel to do so?

sounds like the "diesel used:bhp" ratio shows a fairly frugal Renault engine?

42mpg on a 150hp car unreasonable? id say not to be honest, ive lost 2mpg since december to present with the cold mornings etc...

if you are driving steady 60mph roads then you should be getting more, but general driving duties in towns with plenty of stop/starting and traffic and life in general id say 40-45mpg on a 150 horsepower car was pretty reasonable?

wwaswas
one thing that is recommended with Renault Diesels is to really boot them every now and again - somethign to do with the emissions control stuff getting sooted up if you don't get a bit of pressure going through the turbo and engine.

I'll give that a go, we've not owned the car long and I know that it only covered 300 miles or so in the year leading up to us purchasing it, It has crossed my mind that it needs a good blast to loosen up.

Its in spotless condition for a 4 year old car, perhaps the previous owner drove slowly everywhere.

Audi A3 with PD130 engine in does an real average of ~39mpg.

it is the quattro though which loses a bit..

Passat estate with same engine in, driven the same on the same route does ~47mpg

so your golf produce 40% less power and used 15% less fuel to do so?

sounds like the "diesel used:bhp" ratio shows a fairly frugal Renault engine?

Well, when you put it like that...

But in defense, the Golf was ragged - whereas the Megane is being cosseted around, mainly changing gear at 2000rpm or less.

I did get 55 out of the golf when carefull with it. The figures wouldnt look so good on the Megane if I was heavy on the right pedal.

Now you mention "only did 300 miles in a year" that does suggest that the thingummy clogging up doodah might be an issue for you.

However from my detailed technical knowledge of the gunged up thingummy issue (read an article about a bloke who did sod all miles in his Jag diesel and complained that it had this problem) I'm afraid that giving it a blast at this stage won't help - IIRC (and I may well not tbh) the giving-it-a-blast thing was to stop the problem occurring, and once the problem HAS occurred the solution involved replacing some expensive (in a Jag at least) bits.

There may be someone else with more knowledge on this than I....

2l volvo v70 diesel here..22k on the clock... as just about all my driving is round town now, I am only getting 32mpg 😥

This car will not be with me much longer 😆

Civic 2.2 Diesel, which is quoted at 54 mpg and over the last 2,800 miles has averaged 44.3 according to the on board computer.

Not Miss Daisey driving, but normal driving, not ragged everywhere!

have a look on the renault forums;

[url= http://www.renaultforums.co.uk/showthread.php?t=111310 ]http://www.renaultforums.co.uk/showthread.php?t=111310[/url]

the EGR does seem to get blamed for poor economy.

Jeez, that's poor I reckon.

I had a Megane dci estate as a hire car in Belgium a few years ago - original shape Megane. No idea what engine was in it, but from it's performance, I reckon it had at least 100bhp, probably more..
I got 58mpg from that (computer indicated, admittedly) without even trying. Ratio of urban/motorway, probably 20/80.

My currentl 130bhp Ibiza diesel (1.9 VAG PD engine) does 55mpg when driven 'normally', nearer 60mpg when really being careful & the lowest I have seen was about 44mpg on a erm, spirited drive to Cornwall with two of us in it, 2 weeks of "pack the kitchen sink" camping gear and 2 bikes on the roof!

Many people just drive their cars around at low rpm. They need a bit of exercise!

Give the car an [i]Italian tune-up[/i] (warm it up and drive along in low gear at high rpm for a sustained period, using plenty of welly), it can work wonders.

The more expensive alternative is a [i]German tune-up[/i], which involves driving flat-out down the autobahn as much as possible, which can produce also excellent results and a nice holiday.

Change the air filter, clean the air-flow meter and clean the EGR system.

Be happy with around 50mpg on a run, but don't be expecting miracles.

so your golf produce 40% less power and used 15% less fuel to do so?

No.. the 90 or 140bhp figure is the MAXIMUM bhp. When driving along the amount of bhp you need to maintain a steady speed on the flat depends on the aerodynamics and the tyres. That's why vans are less economical than cars.

The 45mpg or whatever figure is not achieved at max power 🙂

Clogging is a distinct possibility if it's been babied. I do think 42mpg is poor though - my Passat is bigger and auto and I can easily get 42mpg around town, about 38 if I am in really heavy traffic mind.

Urban driving, short journeys (< 4 miles) and cold weather have killed the economy on mine to around 40mpg. (150bhp cdti, probably the same engine)

In the summer i've had 62mpg out of the entire tank driving at around 60mph on motorways.

I think it just depends how its used.

Theres lots of people complaining they don't get the manufacturers figures, i think they've got better at optimising the cars for the economy tests.

Our Golf 2.0 GT (with 100k on the clock) over the last two years has returned an average of 43mpg over 25k. Driving is 80% shortish trips on country lanes and I don't think this is too bad.
Last year I used it to do a 60 mile motorway commute into Manchester (so plenty of queuing for the last 2 miles in) for 2-3 weeks and the best I got was about 58mpg average for one of the trips back home - I was driving fairly softly at about 70mph on the motorway.

I have a 100bhp Megane Diesel and I average 65mpg on the computer.

I do however drive like an old man, I do no more than 70mph on the motorways, I coast a lot, I brake only when I have to and accelerate smoothly and slowly. I also do the above mentioned [i]Italian Tune[/i] once a month to keep everything soot free and running smoothly.

Octavia 1.9 trial 90bhp here. 80% motorways and keep air on off with tyres checked regularly. easily get 60mpg over a tank.

I do all the above with driving style and giving it a run at high revs etc. However, I am known to drive like an old person 🙂

Given that many car speedos are close to 10% over reading does this mean that the odometer is also over reading the distance by nearly 10% making these quoted real life MPGs better than they are in reality?

The MPG displays in vehicles are indicative only of what you are doing at that particular time. To find the true mpg of a car you need to track the mileage against the actual fuel consumption. there's a good app called Road Trip that tracks your mileage and fuel costs and calculates your actual mpg.

For example.. Octavia 1.9 = 14gallon tank.
@60mpg = 840 miles per fill. call it 820 from full to flashing fuel light. Are you getting near to that on a full tank?

One of the problems with comparisons is what defines 'urban'. If it involves lots of stop start, waiting in queues, trafic hold ups then consumption will be a lot less than the 'urban' quoted figs. My commute is often very much the former, taking 45 mins plus to go 7 miles. If the weather is cold/dark/damp and lights, heaters etc on then my 'average' consumption on this 'urban' route is 34mpg. On an 'urban' drive when roads are clearer then i get 45, and on a longer drive then i get 55 plus. 2010 BMW 318d with stop start etc and a lightish right foot.

The MPG displays in vehicles are indicative only of what you are doing at that particular time

Unless you use the average function.... now it may not be accurate of course, but remember also that petrol pumps do not always shut off at the same point so brim-to-brim only works over several tanks.

I have the 175BHP version of your engine in my Megane.

Don't panic - it is about right!

I now consistently get 38MPG from a mix of town and motorway driving.

What I found with mine was that it didn't really loosen up and start producing decent figures until about 35k miles. There was an improvement of about 20% at this point...

Hope this is helpful.

S.

Warm it up, reset the MPG-ometer, drive at 60mph on the motorway and see what economy it gets. Should easily be over 50, probably 60mpg.

That way you know if its a problem with a car, or just the nature of the journeys you are doing.

ssmith1979
I have the 175BHP version of your engine in my Megane.
Don't panic - it is about right!
I now consistently get 38MPG from a mix of town and motorway driving.
What I found with mine was that it didn't really loosen up and start producing decent figures until about 35k miles. There was an improvement of about 20% at this point...
Hope this is helpful.
S.

I understand the principles of driving to achieve good economy and am using many at the moment. Im just used to seeing higher figures quoted (with seeminlgy less effort to produce them) on OBC's (admittedly mainly VAG cars) of 50's & 60's, seeing an average in the 30's on my car was what left me worried.

I'll being going for an Italian style tune on the way home and will keep a close eye on actual figures (havent owned it long enough yet to be sure), I ran some figures earlier and if I get the range the my computer is telling me then I should be getting somewhere between 43 and 45mpg for this current tank.

If it doenst loosen up a bit over time i'll look to have the EGR valve etc cleaned/checked.

If 45mpg is realistic then I can probably live with it, but given the rising price of diesel over petrol it really seems more likely that I should have spent less on a petrol engine.. 🙁 (or plumped for a 2.0 VAG diesel)

I get 40 mpg in my 2l Renault Turbo Diesel. It is in a Trafic van though........

My VAG diesel is supposed to have a new air filter at 30,000 - but changing it at 10k or 15k makes a big difference to low RPM pull and the economy. Service it, then boot it for a good run (when it's warmed up of course) - that'd be my first call.

I drive a Volvo V50 deisel at work as a response car.....with "spirited" driving I can get the dash readout to show the fuel economy as 9mpg....

As far as things clogging up go - the DPF is a good candidate. Even when working properly they will restrict exhaust flow a bit. The car will be set to regenerate it when it gets to say 50% clogged, but it won't go back to zero and if you are doing town driving it'll spend a lot of its time at 20 or 30% clogged I guess.. Not only that but the regeneration itself uses fuel.

If your car spends its time on the motorway thne not only will it not generate much smoke but the exhaust temperature will be enough to clear it out anyway.

Trouble with modern oil burners is they have got them to close to the performance of a petrol and up the HP and the power band and this has decreased the economy, 25 years ago when they were slow off the mark, no turbos and diesel was way cheaper than petrol this is when I was first driving diesels, you would get way better economy, you have to look hard and do plenty of research to find a good frugal diesel these days, Passat are good, friend of mine before his company gave him one of them daft electric/petrol cars was getting 60plus (loads of motorway miles), Im run a Focus TDCI 1.6 Estate and am very please with its economy, ave 49mpg and low down torq. used every day as a work horse.

Fiat Doblo 1.3 turbo, 85 hp.

Mixture of very steep, slow speed stuff and motorways - 45 mpg average.
I'm quite happy with that.

Average speed is only 22mph!

his company gave him one of them daft electric/petrol cars was getting 60plus

I've got a daft petrol electric car, it's more economical than my Passat. 60mpg motorway and never less than 50 even in stop start town. You can keep your 35mpg diesels in traffic.

I also used to have one of these old simple diesels you talk about. 45mpg was about the best I could do. And it only had 75hbhp, compared to my silly electric petrol car with 105bhp.

My 320d does 42mpg in real world driving. No far I've ever driven has got anywhere near advertised figures

deviant - Member
I drive a Volvo V50 deisel at work as a response car.....with "spirited" driving I can get the dash readout to show the fuel economy as 9mpg....

Aye, I checked the average fuel economy on a job 330d the other night and it said it was averaging 22mpg over the last 500 miles

[i]Trouble with modern oil burners is they have got them to close to the performance of a petrol and up the HP and the power band and this has decreased the economy, 25 years ago when they were slow off the mark, no turbos and diesel was way cheaper than petrol this is when I was first driving diesels, you would get way better economy [/i]

Eh? 25 years ago diesels were usually (very) slow and 40mpg if you were lucky. And diesel was never really that much cheaper than petrol.

But I agree that due to the push for turbo-power its only if you drive slowly that you can get the economy that's been 'advertised'.

I get about 23-26mpg out of my Bongo.

MTFU.

But I agree that due to the push for turbo-power its only if you drive slowly that you can get the economy that's been 'advertised'

You don't have to drive slowly, you just need to drive smoothly and with foresight, and not in too much traffic. I can beat the extra-urban figure on my Passat on a motorway run at 70mph, depending on the weather. Not in the Prius though. But I can quite easily beat the combined figures easily in the Passat and in the Prius I can do it in the summertime. Of course in terms of miles there's much more motorway than town.

Had loaner Renault Laguna DCi, was the 1.5 version, could only manage 34mpg average with that! Worst turbo lag and engine ever too.

04 Leon 1.9 150hp - long term average has just dipped under50mpg in this cold weather. That's mainly 13 mile commutes, half of which is dual carriageway and the climate is never switched off. Drive like a saint and don't brake!

Ive got the Megane GT estate 150 dci and find the computer returns around 33MPG (running kids around, 7 mile commute). However on motorways it is superb.
I came from a 1.8 petrol Vauxhall Signum which was really slow and very poor consumption which the computer said was around 32mpg yet i was forever filling it up.
When i first got the Renault i had very similar feelings to yourself but find that i am visiting the petrol station less often, its awesome to drive, looks good and when you put your foot down it really does go.

Got the roof bars on, 3 bikes on roof and was still pleased with the return mpg on an hours run and back down the motorways (driving at 60-70).

[img] [/img]

42mpg for 1.5l diesel is poor, although urban driving isn't particularly economical or good for modern diesels. However changing a car for few mpg difference to "save money" is crazy. Spend it on bikes instead 😀

BTW I get 38ish from my 3.0 diesel, although it does little urban driving and on the motorway 70mph it's doing ~1700rpm.

18.9mpg at an average of 24.2mph in my m3- powwweeeeeeeeer!*

*only posted to wind up the econojunkies

My 130 PD Passat does about 48mpg on a run in the country..however if I have to drive from cold through the town, this drops markedly; diesel engines are big lumps of metal and they don't warm up very quickly tootling along at 10mph

41mpg for a diesel that claims 51 seems normal to me.

My focus tdci claimed 59 and managed 45-50, depending on if you drive like a granny or not.
Friends bmw diesel claims 55 and gets 44 (mostly long journeys).

In contrast, my turbo petrol golf claims 45 and does 44 on average (with the same type of driving as the focus) 😀

55.7 mpg average for a 9hr drive from Cardiff to North Wales and back in my Volvo V50 2.0D on Wednesday. I wasn't hanging about and temp was down between -2 and -5 for the whole journey, so everything electrical was on.

Averages about 44mpg round town and have got over 60mpg on a motorway run. Not bad for a log burner with 70k miles on the clock.

Italian tune once a month

Don't always assume more power = less mpg. You don't have to thrash the nads off a powerful car to get it up a hill for a start.

If I drive my 2tonne 2.5l 170bhp pick-up sensibly (not even driving Miss Daisy mode) I can get 35mpg out of it. Mind you, thrash it and I'll see 27mpg

Hmmm true I got circa 40mpg on my old Aygo but then like Ford (petrol) their quoted figures are pure fantasy.

In contrast, my turbo petrol golf claims 45 and does 44 on average

Interesting, most people seem to think that the turbo petrols are the worst for coming in far lower than expected. Even the dealer told me they were impossible to get anything like the stats. He was struggling to get 35 from a 1.4 Golf.

So to get good MPG out of a modern diesel you have to drive like an old fart and be really careful.

So glad I bought a petrol, at least I know I'm pouring money down the toilet without thinking about it

11 year old 306 HDI estate with 126k and I get 50mpg on mixture of country lanes, A roads and round town and up to 60mpg on long motorway trips. I don't take it particularly easy either.

I'd say the OP is around about on the money for the bhp. Our old A3 tdi 140 did around 35 about town realistically. 50 on a run. The on board was optomistic to say the least.

4 years of sensible driving later it got handed back with an average 38 mpg on the computer. We didnt buy another (and will never).

Getting 28 combined off a 330i. Not quite the 44 I got of a vag 2.0tdi, but it's fast, doesn't sound like a tractor and goes sideways almost at will 🙂

9 year old CLK 270D. 42mpg urban. 60mpg on the motorway.

Im peeved as my 12 year old Golf estate Tdi (90bhp)was thrashed every day and never fell below 47mpg

My car is a year older than this,same engine,same horsepower.. not thrashed but i have continued to get great fuel economy over the years. In the magazines it seemed one of the most economic at the time with something like 62mpg/74mpg! I mostly cruise it up to speed without trying to get there as fast as possible and it averaged out approx 60mpg before xmas.There was a few moments thrown in there too so its still doing amazing for getting close to 1/4 of a million miles!

To the OP.. my car was still feeling tight around 50k. I remember after 60-65k it felt a lot better. I bought mine with 23k come to think of it.. so there you go!

Actually just made the mistake of filling up at Tesco. 34mpg urban, 45mpg on yesterdays motorway run. WTF.

[i]So to get good MPG out of a modern diesel you have to drive like an old fart and be really careful.

So glad I bought a petrol, at least I know I'm pouring money down the toilet without thinking about it [/i]

Yep, 535i here 😆

It might only do 20-25mpg but its pretty much zero depreciation and has a V8 soundtrack - what more could you ask for?

Got 65-70mpg in my old 106 1.5D 60bhp, no turbo.

Get 60-65mpg in my current (but still pretty old, 2001) Clio 1.5D. 65bhp with turbo.

I reckon, if the power/turbo's there youre more likely to use it even if you don't realise.

My 106, I would thrash, well as much as I could and never got less than 60mpg. If I push, but not thrash my Clio, with its turbo I reckon in 40s wouldn't be out the question.

My car gives much better economy since I realised I was calculating mpg using US gallons rather than Imperial gallons.

Laguna estate DCi 150
typical MPG = 39 to 42 ( mostly shortish journeys)

Recently did a trip to Birmingham & due to awful weather conditions, averaged less than 60mph - The MPG returned was 57 !!!
( I was quite impressed)

Periodic Italian tuning does seem to make the engine run better. ( but, ONLY do this when the engine is thoroughly warmed up)

Chris

1.8tdci focus here..

Currently sat at 37mpg.

Got the car when i was commuting 20mi each way, a year ago i got a job which was 3mi each way. Still drove, and the car is still cold by the time i get to work. The car really drinks fuel when it's cold, and sips it when the engine is up to temp. Managed to get to Aberdeen last year from Chester and the car hit 67mpg for the run.

So to get good MPG out of a modern diesel you have to drive like an old fart

No, you don't have to drive slowly, you just have to know what you are doing.

Been pretty happy with the economy of my 325D Touring.. 3 litre straight six with a remap (~250bhp) returns ~43mpg (tank to tank) in mixed driving - not too far off the 47mpg official figure. Seems to respond well to the occasional thrashing too..

I find some of your mpg claims basically incredible. How slowly do you drive? Are these real figures?

Hire car this weekend - 250 mile trip across two cities, 40 miles of A road rest motorway. 28 mpg 🙁 Petrol zafira

My 2003 Passat TDI used to regularly exceed it's quoted book figure, with one memorable occasion averaging 67mpg on a long, slow drive from Manchester to Devon. The BMW, however, quotes up to 70mpg and averages, even being driven carefully on the motorway, 42.

TandemJeremy - Member

I find some of your mpg claims basically incredible. How slowly do you drive? Are these real figures?

My thoughts exactly. The only place I have ever got close to the supposed MPG figures of any of my cars has been in France on very quiet roads.

I find some of your mpg claims basically incredible. How slowly do you drive?

I drive at the speed limit almost all the time, and usually avoiding heavy traffic. You can easily gain 10% fuel economy by paying attention to fuel economy techniques, I reckon.

Oh and on the motorway I use cruise control.

Everyone loves MPG 🙂

Here's a great free site : http://www.fuelly.com/

[quote=TandemJeremy]I find some of your mpg claims basically incredible. How slowly do you drive? Are these real figures?

I drive six inches from the bumper of the car in front to maximise the slipstream effect and don't bother with unnecessary power drains like indicators etc.. 😈

Seriously though.. real-world figures. I don't drive particularly slowly ('keep up with traffic') but I do try and drive as smoothly as possible and anticipate the road ahead - leaving plenty of space on the motorway to minimise the amount of braking/accelerating needed etc. That and the right tyre pressures (a bit over if anything) and no unnecessary crap in the boot.

TandemJeremy - Member
I find some of your mpg claims basically incredible. How slowly do you drive? Are these real figures?

Hire car this weekend - 250 mile trip across two cities, 40 miles of A road rest motorway. 28 mpg Petrol zafira

What engine was it? I think they do a 1.6 Petrol in the Zafira and it wouldn't surprise me if that managed fairly poor mpg figures lugging a heavy MPV about with a large frontal area. The cold weather won't help either.

With the amount of miles I do, I keep a close eye on the mpg figures my car is achieving. It always takes a dive in the cold weather, but I am currently getting about 57mpg give or take. That's calculated from fill-ups. I drive on the A1 mainly on the way to work, and there are two roundabouts where I probably sit for a total of 20mins/day at least. At the moment I stick to 60mph. From last year, I know that during cold weather if I drive at 70mph, then the fuel consumption is probably nearer 52mpg.

In the summer just gone, driving frugally I regularly used to get over 60mpg over a tank, with a high of 63mpg, I think. The computer shows nearer 67mpg though, but I ignore that.

The car is a 1.9TDi Ibiza, with 130bhp & 6 speed gearbox. 70mph sees it revving at about 1750rpm, so on long motorway cruising it's not really trying at all. Still plenty of grunt for overtakes though, just knock it down to fourth and off it goes.....

thanks for all your advice guys, its helped me to realise that I shouldnt have expected quite so much from my car - and that I have been a little naive with regards to potential figures.
I love the way the Megane drives (honestly) so will put up with 40mpg until I can no longer afford to do so!

I've also started to nitice a slight increase in efficiency since the sub zero temps started to fade.

I've got a 1.9 TD Signum, 04 plate and I get on average 46mpg per fill up with keen driving and a little less if heavy footed (reset the average every fill up). Thats a mixture of country lanes, town and duel carridgeway.

Like you said though, as soon as the weather drops my MPG goes really low, annoys me when I have been super keen all the time and it goes down driving exactly the same as before.

My driving style has really changed since caring about MPG and it's surprising how many cars I catch up with over the total journey after they overtake or speed off on the fast bits.

I have a 1.5dci megane estate and currently gettign between 51 and 57 mpg driving it normally. I expect this to go up when the weather impoves and we go back to summer diesel as this seems to make a big difference. For a change the on board comp is indicatting lower than the actual (brim to brim).