Scenic dci 120 with approx 6k on the clock.
The most mpg I am getting is very low 40's whereas the manual says I should be looking at 38.2 / 56.5 / 48.7 respectively for urban, extra urban and Combined.
I can understand that when SWMBO has it for a week at a time doing 2 mile journeys to college then it will be the lower end of the scale. However, the last fortnight I have used it to go to and from work, 1 mile to the motorway then cruising at 60mph for 15 miles and back off for another mile. I have managed to get 42mpg from it!
I had it in at Renault garage who have done emissions test etc and say the engine is doing everything correctly. So what else can I do to my driving style?
I normally switch up gears as soon as I can, rarely go over 70 on motorway. Dealer did say that I should really not go into 6th gear before 50mph as it probably puts more strain on it under 50 than 5th gear does.
RF previously quoted a friend who got high 40s in the same car for a lengthy motorway journey, whereas I got low 40's. For the last few tanks I have had Millers Diesel Plus in it as well but no noticeable effect?
Incidentally, dealer said that the Trafic vans were not deemed to be "broken in" till 15,000 miles but he did say mine should be by now.
Please help me as I am one of those sad anoraks (as SWMBO agrees) that gets more pleasure out of mpg figures than 0-60 figures!
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I recommend that you visit this site: www.sexydog.freeserve.co.uk/driven/economy.html
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hello.
Very good site.
--
(iam not a mechanic)
Martin Winters
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Indeed, a useful site, especially for the likes of me.
However, BobbyG probably knows all these things already.
I wonder if it is just the case that no two engines are identical, and there will always be some that come off the production line that will have some slight flaw, so that they will not be as economical as they should be - and that BobbyG has been unfortunate enough to get one of these.
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Could it be that the effects of SWMBO's short trips are outweighing your sensible habits? That is, they may actually be doing things to the car that affect your use of it, even calculating on the basis of a fresh tankful of fuel. After I reclaimed my Golf from my former partner (for whose use I provided it initially), fuel consumption improved by 25% and has stayed there ever since. Put your tin hat on and suggest that she considers a very healthy half-hour walk to college and back each day.
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Getting a vehicle on the move from rest is one of the major uses of fuel, yet most people then fail to ease off the throttle to the point where it still maintains the required speed and therefore avoid unnecessary fuel consumption.
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What\'s for you won\'t pass you by
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One of the disadvantages of using motorways at 60MPH is on long journeys. At 75MPH I can drive 300 miles in roughly 4 hours. At 60MPH it would take 5 hours.
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One bit of advice on that site is incorrect. I refer to:
"Touch the throttle lightly to accelerate rather than hammering it."
Empirical testing (i.e. actually doing it and measuring rather than theorising) has proven that you should accelerate around your maximum torque revs. Many people find that surprisingly brisk, but it ensures you reach your cruising speeed quicker (but efficiently) and thus spend more time cruising. I agree that this isn't "hammering it", but it certainly isn't "touching the throttle lightly".
V
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Having had quite a few new diesels over the years and logging fuel usage and milage for tax purposes, I found that diesels return their optimum economy only after 20k is on the clock. They seem to take a lot longer than petrol engines to bed in, so with just 6k from new I wouldn't worry yet.
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Bobby G
You wait till its done 12,000 miles before worrying.
"I normally switch up gears as soon as I can, rarely go over 70 on motorway. Dealer did say that I should really not go into 6th gear before 50mph as it probably puts more strain on it under 50 than 5th gear does."
In the intervening 6,000 miles I suggest you start giving the thing some head. I suspect its not been run in quite enthusiasticly enough..
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Cheers for all your suggestions guys, it keeps coming back to the same thing - need to run the car in more which is what I will start to do. Drive it more enthusiastically!
However, it does add another equation to the diesel vs petrol argument for those that are comparing cars over a 3 year period. If what we are saying is that for the first 12000 miles or so then you will not get the expected fuel economy, which after all is one of the main arguments for diesel, then who is going to recalculate the standard formula to take that into account?
I wonder if I am getting much more than a petrol Scenic would be?
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I have an old-shape Scenic dti 100; you're getting reasonably good mpg. Start-stop town driving absolutely hammers mpg, if only the government realised this and got rid of traffic jams, unnecessarily short traffic light "green" periods etc....
I used to get around 47mpg from mine irrespective of type of journey; now that my wife uses it for shopping and school runs etc, fuel economy has dropped to around 35mpg - but this is still loads better than a petrol engine (preceding car of 1.5 litre petrol engine gave around 22mpg under same conditions, and rotted its exhaust every year too....)
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.."if only the government realised this and got rid of traffic jams..."
how do you, or anyone else, suggest this could be achieved, IET?
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Bobby - are we talking car-computed consumption, or calculated from actual miles and litres added by you? If the former, try zeroing the consumption when the engine is warm and you are pootling up the motorway at 60. That should show whether the car is doing/computing anything like the suggested figure.
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I have worked with people who drove the same car (fleet Peugeot 309s) as myself and the fuel consumption one of them achieved was under 30mpg, when I was getting 40mpg (both cars had the 1.3 engine). The type of journey was approx the same, so it came down to a difference in driving style and/or something massively wrong with my colleagues car. I drove two 309s over a period of 7 years and they both returned almost identical mpg. The first 309 covered about 67k miles and the second just under 90k.
As far as an engine being run in is concerned, I have never noticed a great deal of difference in any of the cars I have owned/driven from new. The Xantia 1.9 TD that we have, which is now almost 11 years old, has always returned at least 40mpg from mixed driving. It has now covered about 104k miles.
At about the same time as we bought the Xantia, I bought a 1.4i ZX too, and it also returned around 40mpg from mixed driving, over a period of about 3 years, during which it covered 45k miles.
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A couple of other things to throw in -
Different tyres can make a quite significant difference to fuel economy. As can different sizes, do you have standard or lower profile tyres ?
Make sure your wheel alignment is correct.
Driving style has to be the biggest issue though. (but never buy an auto for fuel economy)
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I am reminded of a friend who was very proud of the first MB he acquired about 15 years ago. His driving style was characterized by a very heavy foot: he was either accelerating hard or braking hard all the time. I don't think he worried about fuel consumption, but then he couldn't answer me when I asked him what engine was in the car . . .
I'm sure there's a lot of that about, but probably not among the the Back Roomers.
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try zeroing the consumption when the engine is warm and you are pootling up the motorway at 60. That should show whether the car is doing/computing anything like the suggested figure.
Andrew, thanks for that suggestion. I will give it a try. The figures I was using were my own calculations from brim to brim but it might be worth doing as you suggest to see what I am getting at a continuous 60mph.
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Further to Andrew's suggestion, I have just been on a 20 mile motorway trip to my sister's and back. I zeroed the computer at beginning of each trip.
Going I got 57.3mpg, on return leg I got 48.7. Both were carried out between 55-60 mph.
I think these look pretty ok figures, the difference being, I think, the direction of the (quite substantial) wind we have just now.
Whilst doing this I was wondering, is it better to sit at a steady 60 even when going up hills or would it be better to increase speed before the hills to carry you up easier? If I was on a bike, I would speed up on the flat or downhill to save me effort on the uphill, although using more energy initially, I would probably feel better at the top of the hill?
Does the same apply to cars?
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Dunno, but to make it worse;
Imagine that there is a part of the road which is a steep, but short incline and then a long, long, descent.
Of course, coming the other way it would be a long, long, ascent and then a short, but steep descent.
Let us assume that all other factors are equal and my car would normally produce 30mpg.
A short butsteep incline will destroy the mpg for that portion. But it can't drop it to much lower than, say, 15mpg. However, the long long descent will up the fueld consumption to 60mpg or higher for quite a long time. Consequently the computer would presumably show quite a favourable consumption average.
The journey in the opposite direction would hold it at 25mpg for the long up hill part for some considerable period of time
and briefly up the consumption to perhaps 100 mpg.
In any case, in the normal course of accelerating and braking the most it can conceivably drop the consumption by is about half (30mpg to 15mpg) but it could increase it dramatcially when slowing for a stop, for example (30mpg upto a silly 200mpg).
Consequently, I think that there are reasonable devices for comparison purposes over periods of time and multiple journeys, but I can't believe that they can be accurate for shorter periods.
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