Hi All,
We have a 3.0l jeep grand cherokee 8 speed diesel towing a 3.3 tonne van, I normally tow in auto normally achieving 16lt to 100 klm travelling 95-98klm p hr. today I was talking another jeep owner who tells me he is achieving 11.8 lt per 100 kl towing a 2.8 van as he was advised to tow in manual!
I would love to get some other opinions on this
Thanks
Bobkat
Bobkat, I would suggest you refer to the owner's manual and see what the manufacturer recommends on how to best tow a trailer/caravan.
I can see no problem with towing in Drive, or manual, depending on the advice of the owner's manual.
Personally, with my vehicle I am in Drive for 80% of the time but do use manual depending on conditions etc. I have covered 260,000Km with my vehicle which includes towing my 2,600Kg van for at least 150,000Km on my full-time travels.
However, comparing fuel consumption figures is fraught with confusion. Not everyone employs the exact same methodology to determine exactly what their consumption is.
Indeed, unless both vehicles are under the exact same conditions, including load being towed, over a number of tankfuls of fuel, then even a change of wind direction from one day to another can greatly influence the consumption obtained.
Cheers - stay well and safe and happy travelling - John
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2006 Discovery 3 TDV6 SE Auto - 2008 23ft Golden Eagle Hunter Some people feel the rain - the others just get wet - Bob Dylan
Fuel consumption when towing depends on a lot of parameters. The main ones are the terrain, wind conditions, weight and speed.
Remember that you are towing an object with aerodynamics of a brick. Accordingly, aerodynamic drag will play a very large factor in consumption. The power to overcome wind drag varies according to the cube of the speed. If you double the speed the required power increases by a factor of 8. The drag is also influenced by the projected area of the caravan, but for now, assume that you are towing the same caravan - same weight, same physical size.
If you travel at 100 km/h, you may get a consumption of, say, 16 L/100 km. Now, if you travel at 90 km/h, the drag will be reduced by a factor of (0.9)cubed = 0.73 times the required power ie possibly 11.7 L/100 km if all the power was used to overcome aerodynamic drag. This is not the case in practice, but you can see where it is heading.
Now, compare the 2 caravans. Having a lighter caravan will help also, because there is a constant drag called friction. Friction is directly proportional to the load (weight) applied. so you can have a factor of 2.8/3.3 = 0.85 times the friction drag for the lighter caravan. Throw in some hills, and suddenly you are dragging 85% of the load up the hills if you are towing a lighter van.
Next is the wind. As mentioned above, aerodynamic drag varies according to the cube of the speed. If you have a 15 km/h wind (that is not very strong) this has a major effect on drag. If it is a headwind, 100 km/h becomes 115 km/h as far as drag is concerned. This is a factor of 1.52 times 100 km/h and no wind. Conversely, if you have a 15 km/h tailwind, this is in effect 85 km/h speed, and you will need 0.61 times the fuel to overcome aerodynamic drag.
Now, if you measure your speed by a GPS and set it at 100 km/h, your speedometer can be out by as much as 6 or 8 km/h (my Pajero is out by 6 km/h @ 100 km/h). So if I drive at 100 km/h indicated on the speedo, I can get much better consumption than if I drive vie the GPS.
Then there is the gear that you drive in. If you have an automatic transmission, is the torque converter locked up, or is it slipping? If you can get a locked torque converter working this will save you fuel because the transmission is not slipping all the time.
To sum up, it is not a simple problem - there are quite a few factors involved before you can compare everything on an equal footing, but the most significant factor in towing a caravan is the SPEED at which you tow (including allowing for headwinds). I generally try to tow at 95 km/h, but I keep a close eye on the mirrors and if I see a truck or a buildup of cars behind me I either pullover to let the pass, or I speed up until I can safely let them pass, because the last thing I want to do is to have someone get impatient and try to pass me, causing a collision with someone else (or me). And as for trucks, they are working, when I am towing my caravan,, I am not working so I try to give them a fair go - the truckies generally appreciate the assistance.
Hi bobcat, I also have the 3ltr diesel and I,m usually towing somewhere around 2.8T, I have very rarely used the manual mode and sometimes on a freeway I have even used my cruise control. I sit between 95 and 100kph and like you I average 16ltrs which I,m fairly happy with. In my opinion you are more likely to affect your consumption by how hard you want to push it especiaally From a standing start or when getting back up to speed after slowing down. It seems that the 90 to 100kph speed seems to be the GCs sweet spot in terms of fuel consumption.
Depends how savy you are mechanicly wise ? They will possibly say to leave it in D . To make it idiot safe . Keep in mind light throttle with a few RPM gives better fuel consumption in higher gear ( load ) with more throttle!!
Hi Bobkat, tell him he's dreaming, even if he never goes over 60 kph. My van weighed around 2.6/ 2.7 ton. With my manual Pajero 16 lph. With my 5 speed WK2 16 lph With my 8 speed jeep 16 lph give or take a bit depending on wind and load. You have instant fuel display on your dash, go from manual to auto 7th gear in manual and auto will use the same amount of fuel at the same speed. Labouring the car in 8th gear can use more fuel.
I now tow a boat half a ton heavier and half a metre higher, the car now lives in 6th gear a lot more and 19lph +. Your fuel figures are very good for your weight.
11/12 lph I use that much towing my box trailer with a bit of weight in it.
I don't think your figures are bad for a tow weight up around the car's limit, presumably including 300+kg on the ball. My Jeep GC is the last of the 5sp (MY13) and tows my 2.1t van averaging 13l/100km in drive (which my handbook advises) at 90kph. Frequent hilly driving included in that. On the flat she'll sip around 11l/100km. Keep an eye on your EVIC for trans temp and manually gear down if it gets much over 90c on gradients. Anyone claiming 11.8l/100km with a 2.8t van would be pretty exceptional/questionable? As you know the 3.0 CRD is powerhouse and would pull the QE2, but like other vehicles, fuel consumption climbs fast at those weights and with liberal use of the turbo.
-- Edited by SouthernComfort on Tuesday 20th of November 2018 08:23:52 AM
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Cheers,
Tony
"Opinion is the medium between ignorance and knowledge" - Plato
Hi All,
Thanks for your replies, especially the last 3. We are full time nomads and I really do find the sweet spot on our jeep at just under 2000rpm.
yes I do realize the equations of drag especially the last time we crossed the nullabor in our then Isuzu Winnebago NPR 350 Alpine 2855. It was a shocker with the head winds.
Iam really happy with our jeep as we have now done 62k and probably 40 k of that at least would have been towing, including 16k in Tassie over 5 months.And yes I did think the guy I was speaking with may have a hole in his pocket ( I am sure you know what I mean) look how many jeeps you see on the road towing now days to toyota compared to say 3-4 years ago.
Again thanks, and stay safe.
see you out in the playground someday.
I am considering the Purchase of a Jeep Grand Cherokee and being a bit of a car nut I have asked heaps of jeep owners a range of questions and on the fuel consumption question I have been told between 13 and 16 litres per 100 K with a van around 2.7 to 3 ton advice on tow speeds is you will use much more fuel with cruise control and less fuel if you use the manual mode in hilly terrain.
I have not been told of any common major problems with the Grand Cherokee and they all say they are extremely comfortable and they love their Jeep several who have had Land-cruisers stated that the Jeep is a better tow vehicle.
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I am considering the Purchase of a Jeep Grand Cherokee and being a bit of a car nut I have asked heaps of jeep owners a range of questions and on the fuel consumption question I have been told between 13 and 16 litres per 100 K with a van around 2.7 to 3 ton advice on tow speeds is you will use much more fuel with cruise control and less fuel if you use the manual mode in hilly terrain. I have not been told of any common major problems with the Grand Cherokee and they all say they are extremely comfortable and they love their Jeep several who have had Land-cruisers stated that the Jeep is a better tow vehicle.
Given that no make is perfect, even those beginning with 'T', Jeeps are damned good value especially at the prices vs. many competitors. Always best to listen to real owners and no one else. It's why they sell well as extremely competent (and comfy) tow vehicles. Sounds like what you've been told so far is pretty much on the mark.
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Cheers,
Tony
"Opinion is the medium between ignorance and knowledge" - Plato
No doubt you take more notice of the number of a particular type of vehicle when you own one. i never realised there were so many Jeep GCs running around especially towing vans. I came out of Bunnings today and there was a guy with his wife having a look at mine, he said that they had a 2014 model and were just wondering whether it was worth their while to buy a new one. I couldnt believe it when he told me that over the last few years they had travelled all over Australia in it pulling a Retreat Fraser van - small world. Interestingly he said that when towing he was advised to leave the transmission in auto but select sports mode something about keeping it in 7th rather than changing up to 8th ? I have no idea whether that has any merit or not as I have never found it necessary to use the sports mode. I bank on getting 16ltrs/100 if I happen to get better than that for whatever reason I count it as a bonus.
I wouldn't always believe what people tell you with regards their fuel consumption either.
In a former life I was a diagnostic test driver in the automotive trade and have disproven some positively outrageous claims made by people who actually really believed their own bs. This was a regular occurrence.
Just to throw in my cents worth. Towing a 2.3T single axle van, my computer tells me I am getting 17/100 towing at 100kms when possible (and more most of the time). Because of bigger tyres the computer does not equate properly. Also as tyres wear their circumference deminishes, so hard to really get a proper figure. But my allowance based on my Oziexplorer trip odometer, and the amount of fuel I put in at "reliable" petrol stations????? I am getting about 13-15/100. All I know is when I travel with other people in lots of different vehicles, and most towing campertrailers or lighter vans, I am using less petrol than all of them. This includes Patrols, LC, Pajero, Rangers, Isuzu and Jeeps. This is also because they travel at slower speeds (80-90). Then I have got as low as 11/100!!They are amazed at how I get such good economy. Its also like a Harley and the Jap bikes. The 1650cc HD was far more economical than my Suzuki 1250cc bandit. Some vehicles are just more frugel than others. In any case who cares what you get?
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16.5 Discovery 4 with a few mods and New Age MR 16' Deluxe
Just to throw in my cents worth. Towing a 2.3T single axle van, my computer tells me I am getting 17/100 towing at 100kms when possible (and more most of the time). Because of bigger tyres the computer does not equate properly. Also as tyres wear their circumference deminishes, so hard to really get a proper figure. But my allowance based on my Oziexplorer trip odometer, and the amount of fuel I put in at "reliable" petrol stations????? I am getting about 13-15/100. All I know is when I travel with other people in lots of different vehicles, and most towing campertrailers or lighter vans, I am using less petrol than all of them. This includes Patrols, LC, Pajero, Rangers, Isuzu and Jeeps. This is also because they travel at slower speeds (80-90). Then I have got as low as 11/100!!They are amazed at how I get such good economy. Its also like a Harley and the Jap bikes. The 1650cc HD was far more economical than my Suzuki 1250cc bandit. Some vehicles are just more frugel than others. In any case who cares what you get?
Just to clarify, is your Disco a V8 petrol or TDV6??
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Cheers,
Tony
"Opinion is the medium between ignorance and knowledge" - Plato
Factory consumption claims for Disco and Jeep Diesels:
Discovery SDV6 8.1 extra urban 9.8 urban
Grand Cherokee (5sp) 7.2 extra urban 10.3 urban
The real governing factor is how you drive 'em!
Our 2014 Nissan Navara runs a similar 3 litre TDV6 7 speed auto when towing our caravan gross combination weight around 5.5 tonnes returns somewhere between 14 plus to 16 plus by measurement to the hundred, around suburban driving when home about 11 but touring very low 9s, not so great but love the power.
I do from passed experiences I feel I am a very economy driver. My last 2 transport driving positions I held for 16 years my trucks were always up near the top for least fuel used per kilometres in fleets using 15 or more of the same models. In motorsport won lots of trophies in economy runs spanning about 25 years.
So yes it depend on a lot of factors including how you drive and your real calculation.
Hi All,
I'm currently on the last leg of a circumnavigation of Tassie, traveled down from Qld. So far we have done about 15,000 km over several trips with our GC/van combo.
The van weighs in at about 2600 kg with water, and I have made to following observations -
The Jeep can handle 95-100 kph towing with no issues, however consumption increases noticeably above about 85kph. We sit on about 95 on good roads because we don't want to hold up traffic, because we don't want to spend all day sitting in the car, and because the car handles it well. On most trips we've got about 16- 16.5 l/100km, although headwinds can make this worse.
In very mountainous, winding territory, the fuel consumption doesn't increase - in a couple of cases it actually improved. I'm speaking about Launceston to St Helen's via Scottsdale/Pyengana, or across the centre via Derwent Bridge. Anyone who has done those trips will understand. Naturally average speed is a LOT lower.
My conclusion is that our van, being off-road sticks way out in the airflow, and creates more drag than most rigs. My friend travelling with us has a D-Max ute, towing a 16' poptop. He gets better economy on the flat highways, and noticeably worse in the hills. I'm going to try to look at adapting a wind deflector with a quick release system when I get time, before our next big trip. Apparently they need to sit as far rearward as possible to be effective. Anyone who has successfully done this, please let me know how.
