"56 plate 1.3 CDTi only gives 48mpg, this is after 15k and a daily commute of 30 miles. Best it's given is 50mpg."
Identical engine in my 55 plate 1.3 Multijet Punto = best, one way 82mpg, 79mpg-120 mile return trip, low 70`s always possible out of town. 62/3 mpg typical of constant 3rd gear city use.
As said though 500lbs lighter than the new Corsa, it`s not hobbled with the weight and power drag of air-con,central locking,electric windows,extra steel and so on.
When you think about it, 500lbs is a side of beef or 250 bags of sugar. Given that, its probably doing well.
Perhaps if customer focus was more on weight and efficiency, spacious lightweight cars could be created without them needing to be packed with `features`.
If things go on as they are, people are going to be driving around in 2 ton mini-tanks with full air scrubbing, positive cabin pressure,totally sealed in climate control, a back up simple air-con system and 300kg tropical fish tanks, to amuse in traffic jams.
:0)
No? not even a twitch of anticipation for a submarine type air scrubber?
(note, an element of humour intended...)
Edited by oilrag on 10/08/2008 at 09:24
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Interesting thread here.
I wonder if those getting good economy like OR are long term diesel owners/drivers, used to non turbo diesels which were extremely economical, and have the feel and patience to keep the revs and throttle use low, in order to keep out of those high power bands between 2.5 and 4 thousand rpm when the fuel pump will send vast quantities of fuel through and the turbo's up to full pressure aiding and abetting the surge.
Are those getting the poorer consumption more recent diesel converts, maybe used to the higher revved driving technique needed to make any sort of progress with a petrol engine.
I'm thinking of just how good or bad my 306 turbo diesel, the avensis too, could be on fuel, keep the revs low below 2200 rpm and the vehicles would just sip fuel, but boot the things, especially the pug, it would fly, but the consumption would drop from 50mpg to 35 or so.
Its very true about this weight and bulk gain, the new corsa is a huge car, barely smaller than astra.
Trouble is customers now want all the goodies and comforts on their cars, and all the time the weights going up, and the more power to shift it, and power only comes from burning fuel.
Cars especially diesel turbo's have become very powerful in recent years, with acceleration unheard of in vehicles for road use even 25 years ago, and a car weighing over a ton that can accelerate from rest to 60 mph in less than 9 secs can only do it by burning fuel, stating the blindingly obvious really, but if drivers are going to make use of this power then fuel consumption will suffer.
Would be very interesting to be driven by OR and then a new diesel convert and see the difference.
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"keep the revs and throttle use low,"
That`s exactly how I drive it GB, as though its an indirect injection, non turbo model, I`m very aware when using any significant turbo boost, for say an uphill motorway sliproad.
Edited by oilrag on 10/08/2008 at 11:27
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I think you've hit the nail on the head, GB, like OR I've been owning and driving diesels for 15 years or so - I don't tend to go above 3krpm and mainly drive within the car's major torque rance 1500/2500rpm...
I often get lifts in minicabs/taxis and it hurts to see the way some people drive diesel cars... no feeling for how the engine works... perhaps thats something my Dad taught me... he was a Commercial Traveller and really looked after his cars and always listened out for sounds that shouldn't be there - and got them fixed quickly! Something thats not taught these days... mechanical sympathy!!
Economy isn't about driving slowly, its about learning how your engine works, where its sweet spots are, is it happy at low revs or is it better in a lower gear, and of course reading the road right....
But driving a diesel IS different to a petrol car, even the same model, and it takes time to learn the differencies... and all engines are different....
Edited by b308 on 10/08/2008 at 11:54
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We had an old shape diesel Corsa as a pool car at work.
Slow, noisy, smelly, no pas - everything people hate, apart from Mr Oily, who would probably describe it as luxurious because it had a heater. :)
But economy? You'd think the fuel gauge had stopped reading, it dropped down that slowly.
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Vauxhall claim in the handbook that my 1.3cdti will do between 48mpg and 74.8mpg. Independant tests rave about how economical they are - 60+mpg, (google "vauxhall corsa mpg" to get any amount of them), but I'm struggling to get near 48mpg under any circumstances. If they were only meant to do 45mpg I would accept it, but probably wouldn't have bought the car in the first place. Either there is a conspiracy going on with Vauxhall and the people doing the tests on these cars, or there's something wrong with mine!
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I don't tend to go above3krpm Economy isn't about driving slowly its about learning how your engine works where its sweet spots are is it happy at low revs or is it better in a lower gear and of course reading the road right....
Spot on 308, and reading of the road is what the vast majority of drivers cannot do.
How often are we approaching a junction or similar that we know we will be stopping for at least one light change, or knowing there will be a queue of several vehicles waiting. Now we hopefully will have lifted off the throttle and coasted the last half mile as we are stopping or at least slowing right down if we time it right, but the bunch of cars in front, train like will be belting up to it under power all the way, then all jam on brakes together, what a waste of time, effort and fuel.
Small example, but multiply that by the dozens of junctions on the average commute and i bet a competent diesel driver could be on overrun for probably 30% longer than the lemming like 'blast and brake' progress of the average driver, and the best of it being progress just as quick.
And i should imagine thats a lot of the reason OR gets his 30% or better fuel economy than the average.
Trouble is how does a younger driver learn this technique.
EDIT. I had a mentor, like you with your dad 308, wonder how many of us more sympathetic owners had someone we respected and learned from.
Edited by gordonbennet on 10/08/2008 at 13:27
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Identical engine in my 55 plate 1.3 Multijet Punto = best one way 82mpg
Interesting - is this the 90 P.S. or 75 P.S. version? Mate's is 90 P.S. And yes he has got climate control, computer etc which adds some weight.
Keeping revs low - I'm not sure in this day and age that's it true. Yes, a car on boost will inject more fuel per second, but given that it's getting you from A to B faster, does this necessarily mean it's injecting more fuel over the distance than the old diesels which will get you there much later.
Modern cars with fly-by-wire throttle should by their very nature be more fuel efficient as they will not allow excess fuel into the engine if it's going to be detrimental to the emissions, hence give poor economy.
The argument about rev range is also slightly flawed. The CDTi engine utilises a variable-geometry turbo to attain turbo boost at most engine revs - there is no longer a surge at 2000rpm like on my Di. And whilst my Corsa cruises at 70 in 5th at
2500rpm, my mate's comes in slightly below 2000rpm with it's 6th gear, which he's been driving at in a vain attempt to better me :-)
Edited by mfarrow on 10/08/2008 at 16:19
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Keeping revs low - I'm not sure in this day and age that's it true.
I did say you need to know your engine and that they are all different - I now have a VW 1.4TDi 80 which replaced a VW 1.9TDi 100 and I have had to make adjustments to my driving to suit the different torque characteristics...
Having said that the 1.4 will still pull nicely from 1500rpm as long as I'm not heavy footed, the 1.9 would pull like a train from those revs, though....
As for keeping revs low, well yes, thats the whole point of a diesel engine, you don't have to revs the nuts off it to get the power, and the less revs you use the better the fuel consumption (most of the time)... the skill is finding the balance between economy and progress!
GB, I have tried to teach my daughter the same as I was taught, though with more limited success! One thing I showed her which many instructors don't teach is the "single finger" gear change! How many times have you seen a driver "fight" the gearbox? I showed her that it is possible to change gear delecately with one finger using the spring loading to the gear leaver to help you - makes you realise that you don't have to fight the car to make smooth progress!! I know you wouldn't do it in real life but it shows that most gearboxes these days can be handled quite gently - especially compared with the old box I had in a '68 Mini 850! ;-)
Edited by b308 on 10/08/2008 at 16:48
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The argument about rev range is also slightly flawed. The CDTi engine utilises a variable-geometry turbo to attain turbo boost at most engine revs - there is no longer a surge at 2000rpm like on my Di. And whilst my Corsa cruises at 70 in 5th at 2500rpm my mate's comes in slightly below 2000rpm with it's 6th gear which he's been driving at in a vain attempt to better me :-)
1.3 Cdti engine in 75bhp form uses a fixed geometry turbo and 90bhp has variable geometry turbo.
My Cdti 75bhp Corsa D is dire below 2000 rpm after which it surges. IMO this is due to the programmed emission limits in the software. I have read that Fiat (who make the engine) have been too conservative in emission limiting.
I also read that the 90bhp engine has now been withdrawn from production due to "terminal turbo lag" - (the poor response of the engine below 2000 rpm)
I bought the 1.3 Cdti as it looked good on paper, but in practice is a very poor performer certainly in 75bhp 119g/km guise. Uses too much fuel (nowhere near manufacturers claims), is noisy at low speed and above 3000rpm, and torque delivery is just too peaky.
In addition I have terrible problems below 1300 rpm with persistent stuttering/hestitation, making use at low speed a frustrating experience. Its not what I expect a diesel to be like.
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I change up at around 2,000 /2,100 revs. That drops the engine speed back to around 1,750/1,800 revs. In other words right at the peak of the torque curve. (70BHP Model)
Further progress through the gears keeps the engine on peak torque and revs only exceed 2,100 when speed rises above it in 5th with no further gear to change into.
Around the City, I run in 2nd/3rd gear at around 1,800/2,000 revs with the engine spinning freely.
Its only a 1.3 so there is little of the non turbo torque that is available from tickover on a large cylinder capacity job. (as a function of cylinder capacity)
It seems to me it must be killing the engine driving it below 1,300 revs.. At least 450 revs under any usable torque.
Driving a turbo diesel outside the peak of the torque curve, when its possible to be on it, is a petrol engine driving technique.
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In addition I have terrible problems below 1300 rpm with persistent stuttering/hestitation making use at low speed a frustrating experience. Its not what I expect a diesel to be like.
Running at 1300 RPM is bad on a whole number of fronts, but particularly that the car isn't under proper control. Change down a gear (or even two) and keep the engine spinning, instead of stuttering / hesitation. I dread to thing what effect such driving has on bearings, drive train, mountings etc. You may well find the car is more economical too, but even if it isn't, a big repair bill will wipe out any savings made by juddering along in the car.
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I keep getting this kind of advice on forums.
Anyone explain to me how I should drive around Sainsbury's/Tesco's car park looking for a parking space and then manouvering into said parking space while keeping the revs at 2000 rpm?
Give me a VAG diesel anyday.
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Anyone explain to me how I should drive around Sainsbury's/Tesco's car park looking for a parking space and then manouvering into said parking space while keeping the revs at 2000 rpm?
I must drive strangely, I think that would be one of the easiest places to keep the revs down. Certainly I tend to idle round in 2nd, so I probably stay under 1300 rpm.
Now a multi-storey, that would be different..
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Hello All,
I've just bought a used Corsa Design 1.7 CDTi. Its just over a year old with 14200 on the clock. I bought the car mainly for the size and fuel consumption. The car was serviced before I purchased it by the dealer.
I've just done my first economy test by filling the tank and seeing what mileage I'm at by the time the light comes on, and its a measly 315 miles! I was expecting AT LEAST 100 miles more. I'm assuming I can probably get another 40/50 miles out of it before its dry.
I drive to work on the M1 every day, varying between 60 and 80 miles an hour in sixth gear, doing around 40 miles a day. I do tend to take advantage of the turbo, but I wouldn't say I abuse it. 3k revs, maybe a tiny bit higher, is when I tend to change gear.
Should I be taking this back to the dealer?
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What mpg is that?
If you " tend to take advantage of the turbo" then you will get lower consumption - I'm getting the impression you like to "push on" - is that fair?
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This low engine speed torque point amuses me. My old Rover 420 had immense tickover torque - you could, on a flat road, simply lift the clutch in 1st not touching the gas pedal at all, let it reach idle speed, then repeat this through all the gears getting up at about 35 mph without ever having touched the gas pedal. You could manage this on a hill even up to 3rd gear.
Ive never had trouble getting near combined figures yet I dont drive slow, just gently - if you want economy, drive economically surely? It doesnt mean crawling along, just means a bit more thought. I get within 1 mpg of my combined figure on the Daihatsu without going to any great lengths to get them. Sometimes on the motorway ( at 80 ) it dips by 4 mpg but thats just not where its gearing works best for it ( much better at 70 ).
That said, certain models such as the Smart are known to have extreme trouble getting near figures - only thing is, these figures are lab tested, so unless you often drive your car in a lab, why would you expect to be able to repeat the figures?
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That's definitely fair, I don't wait around, but I also wouldn't say I hammer it either.
I also have a Ford Focus 1.8 LX TDCI that I used to use for work, and this could easily get me 425 to 450 out of a full tank and that's only 10 litres bigger and over 6 years old. I used to drive that in exactly the same way, in fact I probably drove that a little harder than the corsa.
I purposefully didn't use Air Con etc in the Corsa during this tank, so I could get a good idea of the reading.
I guess I have no choice now but to spend a week driving to work being 'ultra conservative', which is very VERY boring when you drive on the motorway every day. At least then I'll know if its me or the car.
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Must admit that I'm glad I didn't get the Corsa, 'cause it does seem to be getting a bad reputation for consumption - I've had two Fabias and have no probs getting the combined figure and even when pushing on get 50+ in both (one was the 1.9 TDi as well!).
What was the MPG, btw?!
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In my honda accord diesel 2005 executive, I have been consistently getting between 55mpg to 58mpg using shell diesel extra or shell v power diesel by not speeding beyond 70 miles per hour keeping the rev at 2000rpm and using high gear for in town driving. These figures are brim to brim calculations e.g my last tank fill was 52.4 litres for 675. 5 miles. My journey is travelling between Coventry and London on weekends with mix town driving on week days. I use AC while on motorways for only 10mins once a week and from time to time to defrost the windscreen and the windows.
Edited by Akin on 08/09/2008 at 17:25
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Akin, I do very similar, and never get beyond 43. Go figure :-(
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Gordon M, another thing I do is to use Cruise Control because from my own deliberate observation it led to better fuel economy. I also do anticipatory driving looking for red light from a far and stop accelerating from distances. In very slow moving traffic up hill, I initiate movement and leave the car in gear one or two and allow the car to drag along with all the pedals free and the rev is usually sub 1000rpm in this situation (very useful in the traffic congestion between Newcross and Bexleyheath in London)
Edited by Akin on 08/09/2008 at 17:55
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Akin, I can get from 40 up to 43 by being very careful. However, I went nearly 300 miles on motorway, cruise on at 60 mph, aircon off, tyre pressures checked, no roof rack, and mine still only got 43.7 mpg (measured brim to brim). I'm sure there's something wrong, but Honda say no.
I'm slightly sick of it, can you tell?
BTW, apparently the sub-1k rpm thing is a great way to kill the dual mass flywheel. At £500+, that isn't worth it for me, I try and keep above about 1300 and below 2k when I can.
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Gordon M, I am not so versed in tha art of motoring to offer a technical help. However I have cruised at 65mph in the past in order to get a better economy but came worse off. It seems for long distance journeys the best speed is the one that the rpm is 2000 (personal opinion but from diligent observation) and for my car is 66 miles per hour on the car speedometer so probably 60 in real life. I use Castrol 0-30W full synthetic oil. What about using fuel system cleanser like Redek as a one off (I don't use it regularly), it only cost about 3 pounds from supermarket filling stations. From your last reply I would not be doing the sub 1000 rpm anymore. Thank you
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Makes you wonder if the new Fiesta diesel will really average 62 mpg doesnt it?
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I have the same engine in my Astra 2005- I have had it for about 18 months now with about 28k on the clock.
Fuel figures range from approx 51 mpg when pressing on/mostly town driving to a record high of 58.3mpg for a tank when fuel hit 1.29 .
I have not been able to better it since but have come close with a couple of tanks returning just over 57 mpg.
Figures checked by brimming , economy improved using a calibrated Scangauge which is a great tool if you like that sort of thing
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Wont all this pussy-footing around in a diesel clog up the EGR valve / particulate filter in the exhaust? I think I read somewhere on here anecdotal evidence that a good thrash now and againg clears the tubes out and will releasea bit extra economy. Wether you gain it back in better economy (the fuel) after caning it a bit is open to question I suppose.
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Hi all, new here!
I just wondered if there were any updates to this.
I bought an 11 month 4.5K 1.7CDTI Corsa late last year and am struggling to get more than 43-44mpg. I drive very carefully and this is the only diesel since the early 80s that has not given me roughly the quoted overall mpg. I got more from my heavier, faster Almera. The dealer did a test and said he got 60mpg! I suppose they can give any figure they want if they are trying to avoid admitting a problem, even with a pump receipt.
I have now done an extra 2K and no difference.
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Ask him to do the test again with you in the car?
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I was once party to a dealer economy test.
It was a Rover 45 V6 auto. Customer said couldnt get more than 22 mpg and it should do 30. We said ok, so used it as a runner for the service dept. We ran it dry, put a gallon in it and ran it dry again. 33 miles we got out of a gallon and that was alot of fast, mixed driving around town and country.
Im not suggesting you do this test, but what exactly are your methods for measuring?
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I wondered about that and asking if they could keep it longer and use it for their runaround but thought it may just antagonise them.
They only do a test over 50miles and with putting such small amounts of diesel in exactly how they fill it up will be critical, depending if they bother about how much froth/foam is in the system and how fast they fill it. I did my own 50 mile test properly and got exactly the same as all my other tests.
Edited by ash666 on 22/01/2009 at 18:01
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It's been mentioned before but some cars seem to get nearer manufacturers claims than others. I note another contributors good figures with a Fabia - I regularly get much better than quoted on my Golf (2 litre TDi) without trying. I know this doesn't help but it's a poor show if you have to drive more carefully in a Diesel to get the benefits. Kind of defeats the object and you have my (rather useless) sympathy.
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given the relative prices I would have been better off with a petrol car.
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am struggling to get more than 43-44mpg
Fuel computer reading, or brim tank, do some miles, brim again and out with the pocket calculator?
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brim to brim(visible liquid, not pump clicking off) and calculator. I've done it many times now over 2k and every reading 43-44mpg. No hard acceleration, change up early, no high speeds etc.
SQ
Edited by Dynamic Dave on 22/01/2009 at 19:21
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Might be worth waiting until you have some miles on the clock first, some engines take an age to loosen up.
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>>more than 6k than?
Both my last company diesels (Focus TDDi and Megane 1.5 dCi 106) took about a good 10-12k before the economy and performance stopped improving, so probably yes.
The Renault engine's economy improved from 44 mpg average to 54 mpg and it became much gutsier as it ran in. Focus was less noticeable, but still definitely "tight" for a good few thousand miles.
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