fuel consumption

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arry_b
Posts: 519
Joined: 10 Dec 2002, 16:55

Post by arry_b » 15 Dec 2003, 03:21

Devon to Newcastle @ 60-65 MPH 1.9D ZX
BORING! But I got 64 MPG (and work was paying for my time).
For normal running around to work and back I get 46. Seems the cars can be very variable.
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James.UK
Posts: 1169
Joined: 15 Dec 2003, 00:12

Post by James.UK » 20 Dec 2003, 06:13

My ZX 1.9D auto Avantage 1993 5 dr. Does about 30 mpg around town, but thats because it wont go into top gear at less than 40 mph. On the motorway at about 70 mph I get 50-55 mpg, at speeds around 90+ (m5-m6 for 4hrs late at night-early morning) I was down to 38 mpg ish. Overall I ave about 40 mpg ish..
The car is slow to get away from stop, but once on the motorway it really comes into its own. Its great for long 70 mph journeys.
Cheers.. James.
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James.UK
Posts: 1169
Joined: 15 Dec 2003, 00:12

Post by James.UK » 20 Dec 2003, 06:17

My ZX 1.9D auto Avantage 1993 5 dr. Does about 30 mpg around town, but thats because it wont go into top gear at less than 40 mph. On the motorway at about 70 mph I get 50-55 mpg, at speeds around 90+ (m5-m6 for 4hrs late at night-early morning) I was down to 38 mpg ish. Overall I ave about 40 mpg ish..
The car is slow to get away from stop, but once on the motorway it really comes into its own. Its great for long 70 mph journeys.
Cheers.. James.
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mbunting
Posts: 712
Joined: 21 Dec 2001, 16:19

Post by mbunting » 20 Dec 2003, 15:25

Unless the motorway is empty, and therefore you can make progress, it's pointless zooming along once minute, then crawling the next.
Each morning, I do the one of the busiest stretches of the m1 ( 33 or 29 to 26 or 25 ). The number of cars I see zoom past me, only to catch up with them at 27 downwards is funny. I simply sit in the inside lane at 60, not bothering any lorries, there's far less wear and tear on the car ( brakes, tyres, rev stress etc.. ), and your using far less fuel because you're maintaining a) a constand speed and b) a speed which is suitable for the conditions.
I have to make a quick decision sometimes as to whether to get off the motorway and use the various lanes I know of, or stay on in slow traffic. I hate being in jams, but even a constant 40mph is better that variable speeds on back roads for economy.
Typical, I decided not to do some overtime today, and look at the coolant leak instead. It's now chucking it down !!!
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lhm_leak
Posts: 135
Joined: 21 Sep 2003, 02:33

Post by lhm_leak » 21 Dec 2003, 20:34

My TD Xantia consistently returns 48 MPG +/- 2 on my commuting run. I'm not particularly light footed, but I don't cane it either. In contrast, on the same run the 2.0i version manages 33 MPG - I've saved almost as much in fuel as the TD cost me! The run is 50 miles each way on "normal" A roads.
Stu.
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Robin
Posts: 485
Joined: 01 Jan 2004, 19:45

Post by Robin » 02 Jan 2004, 02:14

This mpg thing has been a part of motoring since the days of the Hotchkiss Cowley. I notice mpg is not pushed as much in the publicity as it used to be - could we really be moving backwards on this issue?
In my younger days I used to do economy runs for 'sport' and the major petrol companies sponsored us. My 100k Xantia 1.9TD does very well when I am in the mood and high forties are common with a number of 50 plusses recorded. The best I ever recorded was 50 mpg in a 100E Ford Anglia. Mind you 45 mph was considered quick and 70 really belting it!
I have noticed that many drivers new to diesels drive them just the same way as they drove their petrol cars. The technique is very different especially when accelerating with diesels but modern electronics are beginning to help out here. Just putting the foot to the floor in a diesel is a wonderful way to waste fuel.
In addition the condition of the injectors is also pertinent old or worn ones allowing extended injection instead of a clean shut off leading to fuel wastage. They should be replaced at around 70k miles but at a cost of around £200 it tends to be put off. You can buy a lot of extra fuel for that money. Not what the environment wants though and it is fodder to the environmentalists who think diesel is dirty.
Fuel and air filters are an obvious source of poor economy because the fuel metering assumes a full cylinder charge of air regardless and if not overfuelling results which in turn reduces power and leads to dirty exhaust which clogs the silencers, catalyst and turbo. This reduces the cleansing of the cylinders and added to poor breathing due to dirty filters and you can lose a good 10 mpg through this source alone.
A good blasting down the road will frequently be rewarded with a steady plume of smoke once the system heats up and starts to burn off the soot.
Sorry about the lecture - [:I]
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mbunting
Posts: 712
Joined: 21 Dec 2001, 16:19

Post by mbunting » 02 Jan 2004, 03:17

I think the economy of cars has taken a back seat to the emissions from the cars. However, in the attempt to get Co2 and other emissions down, economy has to go up, to reduce the g/km.
Less fuel used is lower emissions figures.
Hence the development of hybrid diesel-electrics, and technology such as the Golf Ecomatic and the delphi stop-start systems demonstrated on various PSA cars ( although not in production ).
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James.UK
Posts: 1169
Joined: 15 Dec 2003, 00:12

Post by James.UK » 02 Jan 2004, 17:09

Hiya.. So quite how does driving a diesel differ from a petrol car? I have to admit this is my first diesel and I drive it as per normal. I have noticed that on long uphills my technique of putting my foot to the floor and keeping it there, seems to get no results! [:I] lol.. Any tips-advice would be most welcome... [:)]
Cheers James..
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gjb02
Posts: 287
Joined: 20 Jul 2002, 20:37

Post by gjb02 » 02 Jan 2004, 18:16

No real hope there with the 1.9D, I had an Elation 1.9D a few years back, and on a particular stretch of the M4 if someone pulled in front of me whilst I was taking my run up, I'd slow to 50mph and stay there crawling up the hill. Not quite as much torque as it could/should have, I think.
If there's scope for it drop a gear and rev the baby up the hill, the normally aspirated diesel just can't pull that well from mid range revs. The TD on the other hand[:D]
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Robin
Posts: 485
Joined: 01 Jan 2004, 19:45

Post by Robin » 02 Jan 2004, 23:24

The secret with diesels is to use their high and wide torque rev band. With the 1.9 TD that is from around 1500 rpm to 3000 (145 @ 2250rpm & the 2.1 is 184 @ 2000). The 2.1 has wider band from around 1300 to 3000. It is torque that gets you up hills and gives you acceleration.
Compare that figure to the 133 @ 4200rpm in the 2.0 L 16 valve petrol!
So the theory and practice is to drive with the gear selected that gives you around 1500 rpm for acceleration, say in overtaking, and to squeeze the pedal so that you arrive at the floor at the same time as the rev counter hits the red line. However you should NOT do this on a regular basis. Changing up at 2700 to 3000 will give you enough speed in each ascending gear to benefit from the torque available. So you should not have floored the pedal at all. We all do it though!! Try it out, it does take practice and the need to watch the rev counter and not the speedo.
The reason for the difference is that accelerator controls fuel delivery only in a Diesel wheras in a petrol it controls both the air and fuel delivery, wide open is maximum fuel and air taken in direct proportion to engine speed. In a diesel it leads to overfuelling and poor burn which inhibits power output and a smoky exhaust. Just watch the bums of other cars as they floor the pedal to try and get away[}:)]
Approaching a hill can sometimes be a juggle of gear and throttle position but it should not be necessary to use revs above 3k in an intermediate gear unless you are pulling a VERY heavy load. I can do Porlock in third at 3k rpm and frighten a few on the way[}:)]
Just try squeezing the pedal steadily in direct proportion to speed increase and you will soon learn how to relate pedal depression to engine increasing speed to get the best performance.
I have a Porsche 924 for fun and I can give that a run for it's money in the gears from 10 to 70 mph. I do need a rolling start though! Second gear at 1500rpm and push the pedal steadily can fair make a Xantia shift I promise you[:D]
Have fun and enjoy the economy. [;)]
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mbunting
Posts: 712
Joined: 21 Dec 2001, 16:19

Post by mbunting » 05 Jan 2004, 18:34

If you do what Robin has said, and think that the lower the RPM of the engine, usually the less fuel you use, you then begin to see why diesels are so economical.
Incidentally, flooring the accelerator and getting black smoke can actually slow you down, as the unburned diesel will affect the combustion process in the cylinders, resulting in less power and torque, as well as increased fuel consumption.
I tend to gently 'follow' the acceleration of the car by pushing my foot down progressively on the accelerator. If I'm making no progress up a hill, I first lift-off gently to see if that helps ( see above paragraph ), if it doesn't, it's time to change down a gear.
My favourite trick is to sit at 60mph on the inside lane of the M1, not drafting lorries ( usually ). Doing this, I can easily get around 600 miles from a 65 litre tank. Even seen 650 on an even more gentle run.
I once had a Toyota Avensis 1.8i VVT Automatic as a courtesy car for three weeks. I couldn't get it above 27mpg on average ( according to the computer ), but coming back from Milton Keynes up the M1, a gentle drive drafting the occasional lorry, I was getting instant read-outs of 70mpg along the flat, infinite down hills, and approx 25-30mpg up the hills. All using a constant accelerator position. Vary this, and the figures change dramatically. This is also where Cruise Control helps...
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philhoward
x 47

Post by philhoward » 05 Feb 2004, 07:07

Best ever..62mpg Vauxhall Nova 1.5TD; never dropped below 80 for the whole length of the M5.
I had a VW Bora TDI PD 100; didn't matter how i drove it, it always varied between 49 and 52mpg.
Best Petrol? Mini 1100..49.7mpg Wife had a Peugeot 106 1.1i; that would do 42-44mpg all day undertaking Porsches (wifes hobby on the way to Brum Airport in the mornings).
The old Xantia TD did no better that 35-36 on good runs (that was all it had for the 1500 miles I had it); I hope the new one does better (seems to so far; the gauge has hardly moved in 120 miles from the full marker). Also curious what the BX GTi will do; I'm hoping for mid-high 30's...
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AWG
Posts: 82
Joined: 19 Oct 2003, 14:51

Post by AWG » 05 Feb 2004, 14:56

philhoward, You should find your fuel gauge goes into free fall shortly and will be about right at half full or half empty depending on your disposition.
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Russell
Posts: 102
Joined: 20 Jan 2004, 04:15

Post by Russell » 13 Feb 2004, 06:47

Hi,
I think mine are pretty good compared with most on the list.
I get 55mpg from the Peugeot 405 1.8 TD estate at 75-80mph on A14, M6 etc. This car generally averages around 45mpg plus in general use. Not so bad for an old lady with a blown head gasket.
The Citroen XM 2.1 TD drinks more, and is much slower: I'd guess at 10mpg less in general. Needs a good tune up, I think. Why is it so slow..?
cheers
Russell
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Homer
Posts: 1436
Joined: 26 Feb 2003, 11:52
x 5

Post by Homer » 13 Feb 2004, 10:43

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by chizzy</i>

and I know nobody who spends more on alcohol than they do on fuel.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Hmmmmmm well it's close. With the wife being on maternity leave and me walking to work the Xantia only gets filled up about once a fortnight. The monthly stock up of Beer usually runs to a 3 figure sum. Of course that's only around 5% alcohol so technichally It's only a fiver on alcohol.[:D]
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