Hi Suzie,
I can imagine the fuel consumption you would have with your petrol LC would be high and in my experience LPG conversions are great until you have to tow. I always had better consumption when on petrol.
So would a 3litre diesel use less fuel, yes but will it be capably of towing your 3T van. If the van is 3T max never more, then most possibly it will be capable just. I think all the 3L 4x4 wagons are going to be too close to the limit at the least so you would have to look at Utes, possibly Dual Cab Utes but again you will need to read the small print especially if the manufacturer states a GCM (total weight limit of both van and tug). They might quote 3.5T towing capacity but the way the weight can be calculated may result in an actual tow capacity of much less. Unless you can be sure of the actual tow capacity you will need to look further.
So after all this what other options do you have. If it were me either a good 4.2l 100 series LC , a 4.5l diesel 200 series or 76 series wagon. Sorry they are all Toyota but that is the way it is.
This is only my opinion and there will be many out there who will disagree and who are tow 3T vans with 3L diesels, god bless them, but do your own homework on the tug you may select to make sure it will do the job legally before you hand over your hard earned.
And if nothing else this will probably start the replies rolling in to you topic!!!

With regards to the wind deflector, I had good results in the old days in the UK a good 10% saving in fuel as I recall. They were popular until the Turbo Diesels came in. 

I bought one about a year ago when on a special price and tried it on a few trips. I didn't find any fuel saving at all so its stays in the shed. If anyone has had good result I would be interested to here.

With or without the deflector I probably like all get greatly improved fuel consumption traveling at 85 kms compared to 95 or 100 Kms to the point that unless the wind is blowing in the same direction as I am traveling I stay at the slower speed when ever possible. With regards to how much fuel any engine and rig will use is very difficult to state basically there are too many variables such a weight, wind, speed, driving style etc. I have a 3.5t van and 200LC diesel tug, up wind can be 24Lites/100, down wind 17lites/100, at 95km/h on the flat, so you can imagine the number of variables And how they influence fuel consumption. 

Good Luck
Cheers

Nigel

-- Edited by Moonraker on Saturday 13th of June 2015 09:23:53 PM

-- Edited by Moonraker on Saturday 13th of June 2015 09:37:42 PM

Hi Suzie, we tow with a 3 liter turbo diesel, it manages our high set 3.4t van with ease, and the worst consumption we have experienced is 15.8l, but we average 14.6l. The key to towing is not capacity, but torque, and gearing, the more of each you have the better.

The above consumption figures are achieved when towing with the speedo around 100kph (real speed on gps about 96), while I will slow down for safety reason I will not become a mobile road block just to save a couple of bucks in fuel. 

Sorry Plendo, you are right the Disco can tow 3t and more but I would have to disagree with you that torque is not the key to towing but that stability and as such the ability of the tug to handle the load of the van is the prime issue. And I would agree the Disco will do that as well. With the Prado or Pajero 3T would be pushing the limits if even legal.
Cheers
Nigel

Sorry Guys after speaking to hubby he has confirmed the tug is a Landcruiser GXL FZJ105R 4.5 litre dual fuel with the flashlube oiler attachment to aid upper cylinder lubrication and avoid valve burning etc. The van weighs loaded 3.1 tonne and on a recent trip to Cobram Barooga cruising at 90-95 km and not blocking anyone or moving over had a lpg consumption rate of 30 Litres per 100 km and the was after a full recent gas tuneup. Based on that hubby said as long as gas stays UNDER HALF THE PRICE of diesel it makes it equivalent on cost to run but lacks the power boost of the turbo when needed. He was looking at buying a 3lt turbo diesel 2011 Colorado twin cab with rear canopy as a second work vehicle for our company and thought it could at a pinch double up as the Tug.
Appreciate all the good feed back but with him coming out of the automotive industry he'll probably read all discuss it then do what he wants anyway.
Cheers,

SuzieQ52 wrote:

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 just not happy that if we do a huge lap of the map the lpg and fuel costs could be very very high against diesel.

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 I have a friend with a dual fuel Cruiser. When he is able to run it on gas his fuel costs are less than those of us with diesels. There are a lot of places out in the bush where gas is not available. When you average out the total of gas and petrol running you should not be too far behind, certainly not when you consider the cost of changing your vehicle just to save a few sheckles on fuel.

Costs are more expensive if they haven't been serviced properly ! It's mainly fuel filters and oil changes..
On diesels.. On long, heavy trips a diesel is way in front..

Spydermann yes I have one but haven't found any noticeable improvement the few times I tried it. I think I will need to do very accurate trials to find out if it is worth using. So many things can affect it such as how long the tug roof is, where it is located on the roof, thats as far back as possible, the angle, distance between back of tug and front of van, speed. From memory its not needed at speeds of 50mph, which was the towing limit in the UK (80kms) but not many bother about speed limits in the UK, no wind resistance at that speed or less they I guess.
I did use a similar aerofoil in the UK years ago and found a big difference and saving. But that aerofoil was adjustable so could set it up using the fly line method and fitted closer to the car roof, very little gap between roof and foil. You dont see them so often now in the UK because the newer small diesel engines that are very popular over there us next to nothing anyway! Although I did read in a mag when there last year that a few people are starting to try them again. They have been looking in the back of Dads shed to see if they can find one, they were very popular in the 70s and 80s!
I would be interested to hear if anyone has carried out accurate trails.