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MPG improvement tip Disco 3
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PaulP
Joined: 04 May 2007
Location: Barcelona
Posts: 760
 
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simon wrote:and NOT use cruise control
Is this based on experience Simon? If so I find it a bit strange....
I'm asking because I regularly do a 1.5 hour motorway jaunt down the coast (almost every weekend in the summer) and have tried it with the Cruise Control on (at 120km/h) and off (trying to keep it at 120km/h and being careful with the accelerator).
In every single test I've done, I've noticed approximately 5% less fuel consumption with the cruise control on. (±10.0L/100km against ±10.6 with the cruise control OFF).
Can anyone else chip in with their findings? 2006 TDV6 SE Auto Buckingham Blue
2007 Golf GT DSG
1990 Audi 90 2.2E Sport 5-cyl Tornado Red
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 Thu Jun 26 2008 7:35pm |
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dick dastardly
Joined: 29 May 2007
Location: wot satnav says
Posts: 365
 
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Disengaging the alternator might help, but then the battery will go flat in a few hours. There is a water fogging system for putting on the intake side, improves combustion by providing free radicals, helps lower intake temperature for intercooler. See http://www.dragonperformanceuk.com/store/pages.php?pageid=20 when the link works. Not heard of practical experience with it yet though. Probably carp like all these things. Red Indian wisdom: If you must jump canyon, dont do it in 2 steps.
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| Thu Jun 26 2008 7:53pm |
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stapldm
Joined: 11 Sep 2006
Location: In a queue for diesel
Posts: 858
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After some Googling, looks like the aircon compressor is of a different type to the normal slam-on/slam-off electric clutch type. It looks like the pistons are driven by a kind of wobble plate which can be electronically controlled to adjust pumping volume from 0 to 100% depending on the climate control ECU's requirements - that's probably why you don't hear it turning on/off and affecting the engines idle speed.
I guess those fuel savings depend on the amount of work the aircon has to do to reduce the cabin temp to the desired setting as it could be sat there working at just 5% load and hence not show a measurable difference until a whole tank of diesel has been used up.
By the way o nemesis of Penelope Pitstop, whereas you are right in that the alternator can be a major sap of engine power and fuel, please no-one try this at home - The only safe way of disengaging an alternator is to remove the drive belt and cables; which is impractical as you'd need a shorter serpentine belt to keep everything else running. If you run an alternator without the cables connected to a load (= battery) the windings self excite (oooh er!) but without the current flowing the voltage ramps up out of control until all the electronics are killed (almost certainly the voltage regulator and possibly the rectifier pack also). Expensive. Give a man a fire and he's warm for the day. But set fire to him and he's warm for the rest of his life.
Terry Pratchett, Discworld
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| Thu Jun 26 2008 8:39pm |
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andih
Joined: 09 Jun 2008
Location: grantham lincs
Posts: 21
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just thought id add my pennies worth. on my jaunts to kent, i tend to stick my cruise on, and personally, i find she is better on fuel. i have a habit of keeping a/c on econ, but that because having the climate on in my D2 made a big fuel difference, whereas to be honest in my D3 it makes  all difference.
driving round town blah blah i never get less than 28mpg and average 30-31 on the mways.
i do tend to drive her hard ( not thrash) whereas my dad drives a bit more considerate than me and they only get 28 or so from their 55 plate.
you can tell if my mum has driven mine tho, feels like half the engine dont wana work lol. god damn adaptive management thingys lol.
mind you, i dont half get a boll**King when theirs wants to 'get up and go' after ive had her.
but reading this and other bits and bobs, personally, i find the low mpgs quite frightening. mine same now at 16k as she was at 6k.
hey ho. ' ermy' 2007 D3 tdv6 xs java black.
formerly 'eeyore' 1992 D1 200tdi heavily mod
'cherry' 2000 D2 td5 slightly mod. my lil baby for 4 yrs
its nice to be important, but more important to be nice
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| Thu Jun 26 2008 11:26pm |
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simon
Joined: 11 Jan 2005
Location: Do you really need to know ?
Posts: 14410
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PaulP wrote:
Is this based on experience Simon? If so I find it a bit strange...
Yes... spent many an hour on the M40 and M42.
Using the throttle correctly and intelligently is far superior than letting the D3 just maintain a fixed speed. How can it predict a slope approaching ?
Not until is feels its being held back does it start to add the gas... if you see the hil approaching you can add the gas at the right time... maybe its different on an auto ? Dunno.
I just find I can cruise more economically than the D3 can.
Oh, and it can't change gear either... on an auto it will I guess, but on a manual it will labour the engine.
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| Thu Jun 26 2008 11:55pm |
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Craig S-L
Joined: 16 Jul 2007
Location: Tring, Hertfordshire
Posts: 323
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Re the aircon bit.
Of course the compressor/fan consumes energy, and generally that will be a load on the engine, indirectly throught he electrical systema nd the charge being drawn off the alternator. However the aircon/mpg relationship is far more of an issue with old cars (50's and 60's luxury or american cars) where the compressor is huge, or small engined cars, where the load of the compressor is a significant increase compared with the output of the drive train. ie if the compressor pump requires 5hp to run, and the max output of your 1litre 3 cylinder city car is 60hp, then that is a big load.
For most of us, the compressor load is probably less than the general losses in the drive train anyway, and should not be significant. I am sure someone will pop up with the power consumption of the aircon system shortly  Craig
2006 G4 Challenge V8 HSE
Media Support Vehicle Stage 1 & 2 Thailand and Laos
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| Fri Jun 27 2008 12:12pm |
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Robert Page
Joined: 02 Jan 2008
Location: Avalon Beach, FL, USA
Posts: 41
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These are US numbers. My 05 V8 gets significantly better mpg when I drive it manually (no cruise control). I find a 10-15% penalty for using the cruise control especially on country roads. On many stretches where I drive in 6th without cruise control on, the CC keeps the vehicle in 5th gear. I get well over 19 and as high as 21 mpg depending on speed and conditions. Best cruise seems to be around 1900 rpm in 6th or about 65 mph. I drive 3-4000 miles per month. Pulling an 8000 pound car hauler loaded with a Disco II, I get 12 mpg in the flat lands at 65 mph.
I cannot give a lifetime average as my off road mpg sometimes drops to 4-5 mpg!! Guess all that sand and mud actually has some effect on mpg!
Cruise control kills my fuel economy! '05 LR3 (Disco III) Trail, 5 Passenger V8 petrol, LHD, ARB Bull Bar, Warn XD9000 Winch
'99 Disco II, 1.5" OME Lift, OME Shocks, ARB Bull Bar, Warn M8000 Winch (BURNED)
2000 Range Rover SE 4.0 - Bone Stock
'76 IHC Scout II, 345 cid V8, TF27 Auto
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| Tue Jul 01 2008 3:41am |
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TallPaul
Joined: 03 Jan 2008
Location: Reprogramming the W.O.P.A.
Posts: 388
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I think on the aircon front it depends on the relative load to the other loads as Craig says its probably small compared to all the other stuff going on in a D3.
Our other car saves 2-3mpg with aircon off, but thats out of 47 average, our Disco (manual) is getting 27mpg at the moment which makes me unhappy - should be getting more...
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| Tue Jul 01 2008 9:23am |
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ridgeback_moor
Joined: 11 Mar 2008
Location: Devon
Posts: 408
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Since the TorqTune i've been getting about 27mpg average using premium diesel (up from 24 before the TT), but since putting a bottle of diesel fuel system cleaner through it's gone up to 29+ mpg. I did a 420 mile round trip on Saturday mostly at 85 (private roads of course ) and it only dropped to 28.8 average, with 4 pax. At 50 mph steady the mpg increases well into the 30s, but i can't be bothered to drive that slow for long enough to see how good it gets. D3 TDV6 S 2005 - TorqTune, Privacy Glass, Remote FBH, 19" HSE Alloys, Boot liner, retrofit F&R PDC
Defender 90 Truck Cab TD5 2003 - Ifor Williams back, alloys (SWMBO's toy - well, one of them  )
Toyota Yaris 2008 (SWMBO's company shopping trolley)
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| Tue Jul 01 2008 9:44am |
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Spaze
Joined: 05 Jul 2008
Location: Moscow
Posts: 4
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I'm shocked. My new Disco3 is eating too much!
My fuel consuption is 15-17 MPG in the city. I would be happy if it was 25 MPG but it is impossible in our traffic jams.
You are discussing "out of city" mode or you are not have traffic jams in your countries.... What for average speed? Mine is 10-12 mph. I think it is worth to tell your average MPH with MPG. Every user has different values....
Thanks.
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| Mon Jul 07 2008 8:34am |
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COMMANDO
Joined: 09 Oct 2006
Location: CARNFORTH
Posts: 55
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The starter of this thread stated that he used Slick 50 in his engine.This is very dangerous and blocks up the oil pump which can lead to engine failure.Tests done years ago have shown this.Modern oils do not need any additives.
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| Wed Jul 09 2008 11:33am |
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tanters
Joined: 24 Oct 2007
Location: Up The Deise!
Posts: 655
 
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last week my average MPG was 35-36..............took off intercooler cover so maybe extra air helping out 
Anyway, put on a new set of Cooper ST's on Saturday and MPG is....wait for it.....24/ 25 !!!! WTF 
So, off to France soon so will be swapping back for that trip anyway.
Coopers will be sent to their room until they promise to behave themselves
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| Wed Jul 09 2008 12:43pm |
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ronp
Joined: 29 Nov 2006
Location: Lost in my own space!
Posts: 4120
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Since getting my D3 back from its big 105k mile service, the mpg has dropped from around 28 to 26!!
WTF!!!
Just need to check they've not dumped my K&N filter  Blessed are the cracked, for they shall let in the light.
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Morphy Richards 7w "Dual" Food Processor
[complete with addittional bowl and changeable blades]
Only 70p at a store near you!
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 "The BEAST"
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| Wed Jul 09 2008 1:00pm |
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