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jonesy63
Member Since: 17 Oct 2006
Location: Didn't we have a lovely time, the day we went to ...
Posts: 848
  
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Just a data point for reference.
My previous best effort for fuel economy was 8.0L/100km for a Sydney-Canberra-Sydney trip on the one day in 2007. That was with cruise control set at 110km/h, with auto in normal drive position. This was also on the standard Wrangler tyres, no roof racks and RAI.
Last weekend, I sat "shotgun" while my son drove to Goulburn and back on his Learner's license - which limits him to 80km/h. As a result of the lower speed - I got 7.6L/100km - with 265/60R18 tyres, RAI and 3 Rhino Rack crossbars on. It also ticked over 71,000km - so maybe having the engine run-in also offset this. Then there is the brand-new complete fuel system installed too - but I won't dig up those memories! 
Anyhow - pretty happy about that! 8) 
Cheers,
Rob
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 2nd Jul 2009 3:15 am |
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Bushwanderer
Member Since: 27 Nov 2007
Location: Northern Rivers, NSW, Australia
Posts: 2050
 
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Keep smilin'  The Bearded Dragon
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| 2nd Jul 2009 3:42 am |
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rmp
Member Since: 15 Jan 2009
Location: Melbourne, Victoria
Posts: 73
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Was that calculated using the bowser, or just reading the display which is generally somewhat optimistic? --
Robert
Life is better in low range
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| 2nd Jul 2009 11:27 am |
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jonesy63
Member Since: 17 Oct 2006
Location: Didn't we have a lovely time, the day we went to ...
Posts: 848
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rmp - low tech, optimistic dashboard display. Still - not to be sneezed at!
Peter - life is good! 
(Jonesy quickly looks for some wood to touch!) 
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| 2nd Jul 2009 11:45 am |
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Hopperoo101
Member Since: 19 Dec 2007
Location: Canberra
Posts: 20
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Jonesy,
I picked our TDV6 SE up in Sydney last weekend (with full tank from dealership) and drove back to Canberra with the cruise set on 125Kph @2200 revs and the computer was hovering between 11 - 11.4 L/100Km.
Vehicle has done 5000kms. This weeks driving around Canberra has dropped the overal average (still on same tankfull) to 10L/100kms.
This indicates to me that @ 125Kph its working a little too hard if it's using more fuel at that speed than around the city.
Your thoughts & experiences appreciated.
Dennis.
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| 2nd Jul 2009 12:02 pm |
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caverD3
Member Since: 03 Jul 2006
Location: Oberon, NSW
Posts: 6922
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125kph on the Hume Hghway in the ski season.  You're a braver man than me. “There are only three sports: bullfighting, motor racing, and mountaineering; all the rest are merely gamesâ€
Ernest Hemmingway
D4 3.0 Active Diff, Adaptive Lights, High Beam Assist, Surround Cameras, Privacy Glass.
D3 2.7:Adaptive Headlights,Electronic Rear Diff,ARB Bar,Blaupunkt Speakers,JVC Powered Subwoofer,Removable Snorkel,Mitch Hitch,Pioneer After Market Head Unit,Steering Wheel Control Adaptor,Remote Adjustable Supension Rod System, Taxside Dual Battery System.
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| 2nd Jul 2009 12:30 pm |
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Renton
Member Since: 13 Jan 2009
Location: Somewhere in the middle
Posts: 1718
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Dennis,
10L/100Km is the average I am doing as well over the last 20K Km, so that is normal. However if I drive faster (between 130 and 140Kph) on the highway I use about 10.5L/100Km. So your 11+L at a speed of 125Kph seems a lot. Which tyres do you use?
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| 2nd Jul 2009 1:15 pm |
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Dan W
Member Since: 21 Jun 2008
Location: Brisbane
Posts: 355
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I recall a physics lesson back in high school which worked out that the optimal speed (fuel consumption v's speed) was 90km an hour.
Beyond that the fuel (or work) to push a car through the air becomes disproportionately higher. Ie the difference between 90 and 100km is a lot greater than the difference between 80 and 90.
I regaularly get a dash readout of 7.8l/100 out on the highway at 110km/hr but as soon as the rhino bars and surfboard go on it never gets below 9.
I've tried calculating it manually but I always forget to reset the computer when i fill up, however, last year going to the snow (Brisbane to Thredbo and Back) I was getting around 1000km to the tank so my dash readout can't be too far off. 2012 MY13 SDV6 SE D4 Ipanema Sand with Almond leather
2012 TDI Passat - they reckon the DSG is crap, I reckon it's awesome
2010 MY11 Mitsubishi Challenger - Gone (it was a "Challenging Year")
2007 MY08 TDV6 SE - gone
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| 2nd Jul 2009 1:20 pm |
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Renton
Member Since: 13 Jan 2009
Location: Somewhere in the middle
Posts: 1718
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Thats prety amazing Dan. What would your average speed be about?
What kind of tyres?
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| 2nd Jul 2009 1:25 pm |
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Jamo
Member Since: 18 Jan 2006
Location: Esperance, Western Australia
Posts: 1170
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I've generally found with mine that it gets signficantly better fuel economy between 70kph and 90kph.
Some time ago I drove 200km, being 100km bitumen and 100km gravel out and then took the same roads back again. Going out I did 110kph. Coming back I sat between 80 and 90 and, according to the trip meter, I had more range left at the end of the 200km return leg than I did at the start of that leg. Have a nice day!
2010 Cayenne Diesel with PASM & Off Road Pkg
2005 HSE D3 (Sold)
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| 2nd Jul 2009 2:56 pm |
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Rob Hollonds
Member Since: 23 Nov 2008
Location: Sydney
Posts: 69
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My urban fuel consumption (TDV6) stop start peak driving exclusively has increased markedly from around 12.7 l/100 klms to high 14's since fitting Cooper S/T's. (previously OEM Wranglers) Legal freeway speeds increased from 9.5 to abt 10.4. Can anyone suggest this being normal? MY07 D3, TDV6S; Bull Bar, Cooper S/T's, Dual Battery, UHF, GPS; 03 D2, 94 D1, both departed & 1950 S1 80" going strong. 06 Astra CDX Coupe.
Humanity has no capacity to influence the global tidal wave of cyclical climate change!!!!
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| 2nd Jul 2009 10:48 pm |
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rmp
Member Since: 15 Jan 2009
Location: Melbourne, Victoria
Posts: 73
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The optimal speed for fuel economy varies according to the car and the conditions. It won't be 90kph in a D3. So many factors, including environmental such as temperature and wind play a factor.
The biggest factor at cruise speeds is drag, or air resistance. This increases with the square of the speed, eg from 30kph to 60 the drag doesn't double, it goes up by a factor of 4. From 30 to 90 triple speed, NINE times the drag. The mechanical losses and tyre deformation losses do not increase at the same rate therefore drag quickly becomes the significant factor for fuel encomoy at speeds over say 40 to 80kmph depending on the vehicle. This is why there is quite a difference between 110 and 100kph, and even more down to around 70. This is also why a 125kmph cruise could use more fuel than around town, even though accleration is the enemy of fuel consumption.
Typical max-range speed is whatever the engine can comfortably manage in top gear at low revs with the torque convertor locked up.
Any fuel consumption figure quoted needs to be calibrated as the internal gauges are inaccurate. Only way to do it is via the bowser, or do that a few times then you know how far out your gauge is. Pretty simple just make a note of the fill and kays, then do some maths.
Offroad tyres are not only heavier but have an inefficient tread pattern for fuel economy so you can expect a decrease. As they are heavier construction run slightly higher pressures to as per the tyre card and that will help. --
Robert
Life is better in low range
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| 2nd Jul 2009 11:03 pm |
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caverD3
Member Since: 03 Jul 2006
Location: Oberon, NSW
Posts: 6922
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Rob Hollonds wrote:My urban fuel consumption (TDV6) stop start peak driving exclusively has increased markedly from around 12.7 l/100 klms to high 14's since fitting Cooper S/T's. (previously OEM Wranglers) Legal freeway speeds increased from 9.5 to abt 10.4. Can anyone suggest this being normal?
Sounds similar to my experience. The fuel economy returned after i had the turbo and transmission software patches done. “There are only three sports: bullfighting, motor racing, and mountaineering; all the rest are merely gamesâ€
Ernest Hemmingway
D4 3.0 Active Diff, Adaptive Lights, High Beam Assist, Surround Cameras, Privacy Glass.
D3 2.7:Adaptive Headlights,Electronic Rear Diff,ARB Bar,Blaupunkt Speakers,JVC Powered Subwoofer,Removable Snorkel,Mitch Hitch,Pioneer After Market Head Unit,Steering Wheel Control Adaptor,Remote Adjustable Supension Rod System, Taxside Dual Battery System.
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| 3rd Jul 2009 1:06 am |
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Dan W
Member Since: 21 Jun 2008
Location: Brisbane
Posts: 355
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Renton I still have the OEM Wranglers and sat on 110km/hr most of the way.
Mine sits on 13L/100 for city driving, but I leave mine in fast mode so I can cane it at the lights!
I'm off to Thredbo again in early september so I'll do the manual calcs then.
Don't the kids just love a 2800km round trip!! 2012 MY13 SDV6 SE D4 Ipanema Sand with Almond leather
2012 TDI Passat - they reckon the DSG is crap, I reckon it's awesome
2010 MY11 Mitsubishi Challenger - Gone (it was a "Challenging Year")
2007 MY08 TDV6 SE - gone
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| 3rd Jul 2009 11:00 am |
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Renton
Member Since: 13 Jan 2009
Location: Somewhere in the middle
Posts: 1718
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Thanks Dan. I am doing a 5000Km round trip to South Portugal this holiday so an ideal opportunity to get a good reading on fuel consumption.
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| 3rd Jul 2009 11:23 am |
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