When it comes to heading bush with your mates, an age old argument is how much fuel your truck uses compared to your mates. We have had this argument many times at 4WD Action HQ with such a wide variety of trucks amongst the boys and they all reckon that theirs gets better economy than the next.
To set the record straight we are going to carry out five different tests on two of the most popular trucks in the Action stables. We are going to use a 1HZ manual 80 Series Cruiser with aftermarket turbo and put that against a newer 3.0L auto common-rail GU Patrol. We’ll simulate everything from completely empty to fully loaded and everything in-between. We have mapped out a route that has freeway driving, big hill climbs and stop start traffic all to show you what the difference really is between good and bad economy. The one catch is we aren’t going to compromise on off-road ability or spend any money on anything aside from fuel. Let’s get into it!
JUST GOT HOME
We have all been out bush all weekend and gotten home late on a Sunday night, only to say ahh bugger it I’ll unpack the truck tomorrow. If you lot are anything like us, tomorrow turns into next week and so on, right up till the point we are ready to go away again (which could be a month later). Let’s find out how much fuel your truck actually uses with all of your gear still loaded inside and on the roof. One hour to save $100, it’s a no brainer!
80 SERIES LANDCRUISER
With all of the gear and jerry cans on the roof from the last trip, we filled the Cruiser up to our reference point in the filler neck (this was the breather on the both 4WDs). We mapped out our designated run, which included freeway driving at 90km/h and 110km/h, a big hill climb and gradual inclines. With the tyres checked (found three at 35psi and one at 32psi) we set off run to see what we got out of the big Cruiser. Once we got back and topped the tank back up to our marker point, we found that the 1HZ powered Toyota used 17.8L of fuel to do our 104km test run.
We shifted all of the gear off the roof of the Cruiser onto the Patrol (just to make sure we had the same amount of drag) topped up the tank to our reference point, checked our tyre pressures (the rears had 32psi and the front had 34psi in the left and 36psi in the right) and set off on our test circuit. We came back and topped the tank back up to our reference point and found the Patrol had used 13.31L to do our 104km, that’s about 4L/100km difference between old and new.
DO TYRE PRESSURES AFFECT FUEL ECONOMY?
One of the biggest factors when it comes to fuel economy is increased rolling resistance. Just think about what your tyres do when they are let down when you’re driving on the beach or a muddy track. That’s right, they get longer and wider which of course increases your 4WD’s rolling resistance. This is going to give you a lot more drag and will use more fuel to push your 4WD along. In this test we show you what we get running 45psi in the tyres to make up for the extra weight, but still have all of our gear inside and on the roof to simulate a real-world scenario where you’ll want to be using this available space..
80 SERIES LANDCRUISER
With our tank topped up to our reference point, we pumped all of the tyres up to 45psi (normal road pressure for tyres 33inch and up is approximately 38psi) as this gave us less bag on the sidewall of the tyre and created less rolling resistance. Once the truck was set up how we wanted it, we set off on our designated route. Upon return we topped up the fuel to our reference point and found that the Cruiser had used 16L/100km on this trip. That is a fraction under 1.8L less per 100km just by pumping up the tyres. 1.8L isn’t a huge difference, but to think that all we did was pump up the tyres, it is interesting to see what other figures we can get as we test further.
Once we finished the Cruiser it was time to take the GU for a run again, so we pumped the tyres up to our 45psi mark and set off on our run. We could feel the difference in the handling of the Patrol (remember it only had an average of 34psi in the tyres on the first run). The big auto Patrol was rolling a lot more freely and was revving a couple of hundred rpm lower on this run. Once we got back from our run we topped up the tank to our reference point and found the GU had used 12.14L/100 on this trip. Again not a huge difference but 1.2L/100km saved, just by pumping up the tyres.
REDUCING WIND DRAG
How much difference is there by taking the jerry cans, space case and swags on the roof off? Being that neither the 80 nor GU are aerodynamic weapons at the best of times, how much more fuel are you chewing up with the roof loaded up?
80 SERIES LANDCRUISER
We unloaded everything off the roof of the 80 and headed off on another run. The difference in the handling of the Cruiser was unbelievable, you could feel it wanting to fight the wind and move around in the lane with everything on the roof. This time it was not trying to change lanes on us doing 110km/h and it was revving a couple of hundred RPM lower, but still doing the same speed. We got back and topped it up to our reference point; it had used 14.6L/100 on this trip. This was 3L/100 less than our first base test and we still haven’t spent any money to modify anything, all we have done is general maintenance and unloaded unnecessary gear off the roof.
We unloaded the gear off the roof of the GU and set off on our next trip along our test route. Again, just like the 80 you could feel the difference between having gear on the roof rack to it being empty. This was apparent especially at 110km/h as the GU was very loose with everything on the roof and this time it had dropped another couple of hundred RPM and felt a lot more stable. Once we got back, we topped up the tank to our reference point and found that the GU had still used 11.91L/100, a drop of 1.4L/100km from our original base test.
REDUCING THE WEIGHT
Okay, this time we culled all of the gear that has accumulated in the back of the 80 Series. This is so we can test both 4WDs to see what the difference is between having your fridge and a toolbox plus recovery gear and whatever else you may have buried under your back seat. As opposed to, just having the bare essentials.
80 SERIES LANDCRUISER
The 80 Series had three toolboxes, a fridge, an esky, a 3mx3m pop-up awning, a 10l cast iron camp oven and half a dozen different power tools in cases and then it also had both drawers full of gear. We emptied all of the big unnecessary day to day stuff out and stacked in a pile that ended up being about nearly a metre high. With everything unloaded we set off on another run to see if less weight makes much of a difference. On this trip the 80 didn’t feel any different than the previous test, but when we got back and topped it up it had used 13.14L/100. That was 1.5L/100 less than the previous trip and 4.7L/100 less than our first test.
The GU is the 4WD Action workhorse and is always loaded with camera and camping gear and this time was no different. We unloaded a 65L fridge, an esky, two tents, and awning, two tables and a couple of camp chairs out of the back seat and the cargo area. Once it was empty we set off on our trip, it didn’t feel any different than the previous trip and the RPM was the same so we weren’t expecting a big difference in fuel economy. We were right; it still used 11.31L/100. It’s not as much of a difference as we found with the 80 but still a 2L/100 difference from the first test and we still haven’t spent any money or modified anything.