Towing heavy loads with WH Grand Cherokee

[Nift Nev]

I want to compare fuel useage with other Jeep users with a similar car to mine. I own a 2006 WH Grand Cherokee Laredo. It's a CRD 3 Litre diesel. It's only travelled 35,00 km's ( we have another family car). I have had it since new and the economy without towing is 11/100 at 110 kph on the freeway. I just bought a new 2.5 Tonne Roadstar off road caravan this week and towed it (empty) 200 kms to my home. The jeep towed it ok but I was a little startled at the fuel economy of 21/100 under good highway conditions and did not use the cruise control. I travelled around 90 kph in 4th gear(did not want to stress the drive train) and am not a heavy foot on the accellerator. Others say it should get around 17/100. The fuel useage does seem high compared to what drivers of other makes are alleging. They might be pulling my leg. Is there anyone else who tows similar loads and gets fuel useage similar, better or worse than mine? Hate to think that I would need to take a fuel bowser with me when I take the van a little deeper into the outback. Your thoughts and advice would be appreciated.

[drover]

90kph in 4th would probably do it, under 80 or big hills always good to knock em out of O/D but down the highway leave it in D should improve your economy.
35,000km still have that new car smell, that's nearly what mine does in a year.

[Hanna]

Yeah, agree with Drover as the diesel should have enough low-down torque to pull the van along a normal highway/freeway at 90+.

Also, is that actual economy figures or just going by the trip computer? Trip computers are rarely very accurate and it would be worth checking the "real" figure to confirm.

[jeeptrout]

Mate - I own a KJ but also tow a 2.5t boat on occasion. What I found is:
Try to keep the revs within the Max Torque range of your engine, mine is about 1700 to 2300rpm. If that means you end up going slow up hills, thats fine.

Speeds under 80 keep OD off. The transmission seems to hold gears better when OD is off and revs out less. So going up a steep hill under 80kms I would have pressed the OD off button. Over 80 keep it on but watch the revs and you'll waste fuel if the torque converter is winding up the revs.

Your manual will outline the maximum torque range of your car, drive within that range and you will use less fuel. It's harder to do with an auto - thats why generally manuals are a better option for towing as you have full control over gear changes.

[pmac]

I tow two vans with my WH CRD. One I get about 14.8l/100km and other about 17. I just put it in Drive and sit on about 95-100. I also get about 11 without van, so I don't think you have a problem. I'd say it was being in 4th reving higher.

Also - I think it's the shape of the van just as much as the weight. The one where I get 14.8 is lower with a slanty front. The other one whilst bigger is not much heavier is like a block of flats, so no aerodynamics at all.

[hills46]

I regularly tow a boat which has a trailer wieght of 2200 - 2500kg (depending on how much fuel, water, dive gear etc is on board) and has a huge frontal area. Top of the boat windscreen is about 2m above the roof of the Jeep! On level road I get generally around 16 l/100km sitting on 90 - 100.

I need to be doing at least 90 for it to hold top gear though I can encourage into top gear with the shifter at 90 but the silghtest incline or breeze and it just drops back to 4th.

Headwinds make a huge difference. Any significant breeze and the economy rapidly drops to 20+ l/100km so in those circumstances I just give up and sit on 80 in 4th.

Trout, the WH CRD has the QDII so, unlike a traditional auto, the driveline is always locked except when changing gear or taking off. No torque converter slippage to worry about.

[DarwinDave]

Hi all, I agree with PMAC. I completed a 20K round Australia trip last year with my 2007 WH CRD towing a 21' Off Road van almost 3 tonne. From Brisbane to Darwin via the Channel Country in western Qld (about 400km of rough dirt road straight after the floods) I averaged 16.9l/100. that was with the standard ECU tuning. Whilst in Darwin I re-programmed the ECU withan Eco Tune frof CRDStu. For the rest of the trip via the Gibb River Rd and down the WA coast (vi Karajini Gorge) Perth Albany, Esperance accross the Nullabor via Adelaide then through Broken Hill and back to Brisbane; I averaged 16.9 again. The best figures towing were 16.8 and the worst 17.4l/100. The overall average including city driving without towing was 15.9 l/100.
The averages were calculated from actual mileage and fuel purchased which I added to a spreadsheet as I went. The vehicle trip computer was constantly reporting consumption figures in the order of 1.5 l/100 higher than those calculated.
Get those figures out of your V8 Landcruiser.
my driving was 95-100 kph in 5th gear and when revs got down to about 2000 I manually shifted to 4th so that I was always in the optimum rev range.
Highway driving, without towing I get between 10.5 1nd 11 l/100 and around Bris in heavy traffic around the 14 l/100.
The car has a 2" lift and I had an Airflow snorkel fitted by CRDStu before leaving Brisbane and has just turned over 96,000 K's.

Cheers
Dave