How to improve (reduce) diesel usage

[Brett1979 Avid PP Poster! Find all posts View Profile Close Brett1979]

My 90 series petrol auto used 16L/100km mixed Hwy/city & it had a roof cage, steel b’bar, winch, 2x batteries, susp lift & larger dia MT tyres too. I drove it economically. My 120 series petrol uses 15L/100km mixed Hwy/city & has a roof rack, 2x batteries, susp lift & larger dia tyres. I don’t drive it all that economically. What’s your driving style like? Is it always tame? I guess what I’m trying to say is some people’s version of economical driving is still with a heavyish right foot. You mentioned you live in Darwin and do 100kmh in light traffic... Do you use a Hwy that has a 130kmh speed limit (on the way to Palmerston for eg)? I’ve seen plenty of people drive that stretch doing 150kmh. The most likely thing to effect fuel economy that bad is driving style. More throttle means more fuel gets used. Not too good if you’re in the realms of petrol engine fuel usage, and given that diesel is 30% dearer than unleaded in quite of few places at the moment.

[beerad Lurker Find all posts View Profile Close beerad]

Hi guys,
Thought i'd add my two cents worth to this discussion....
I've got a 2018 2.8 150 with BFG 285/70R17, ARB bar, dual batt, Safari snorkel, rhino pioneer rack, 2" lift and i get around 11.5-12L/100km around town.
However when towing a Jayco Pop-Up (Flamingo) - probably 1.4T on the highway at 100Kmh i'm easily reaching 21-23L/100km.... that's not good! that's on the flat with torque converter locked in 4th gear (sport). Up hills is another story.

I'm trying to determine if this is to be expected with near 33" tyres, 2" lift, roofrack etc etc... don't mind the 11-12L around town, but towing chews the juice!

I'm contemplating a Steinbauer or re-map/tune to possibly fix this high consumption on towing.... any thoughts on whether chip or tune would help this?

I reckon the tyres are the main culprit, couple sizes up from standard... along with the other accessories... but maybe with more power the engine won't work at much, therefore lower consumption.
I got a snorkel fitted to help as well, no change to fuel consumption though.

Cheers,
Brad

[RPP Senior Member Find all posts View Profile Close RPP]

Its the tires.
I have the same 2018 150, lift, snorkel, winch, bullbar, twin wheel carrier, drawers. dual battery etc.

Factory tires&rims 265/65R17 around the city = about 8.6ltr/100
Toyo ATs on steel rims 265/70R17 around the city = about 9.7ltr/100. Fully loaded at 3.05t at highway speeds = around 12-13ltr/100 (nothing on the roof rack).

[beerad Lurker Find all posts View Profile Close beerad]

Its the tires.
I have the same 2018 150, lift, snorkel, winch, bullbar, twin wheel carrier, drawers. dual battery etc.

Factory tires&rims 265/65R17 around the city = about 8.6ltr/100
Toyo ATs on steel rims 265/70R17 around the city = about 9.7ltr/100. Fully loaded at 3.05t at highway speeds = around 12-13ltr/100 (nothing on the roof rack).

Wow. That's a huge difference hey. When you say 3T highway? is that towing anything or just fully loaded vehicle?
If that's not towing, i'd be very interested in your towing figures...

I'm starting to think i'm going to have to downsize.... might play the need more power card first with the missus and get a steinbauer haha

[RPP Senior Member Find all posts View Profile Close RPP]

No towing involved, I doubt if I will be towing any time soon.

When taking off at the lights around town I keep the acceleration down and the Eco light on, that keeps fuel consumption under control as well.
More power = more fuel.
On those long trips cruise control will drive fuel consumption also.

The real fuel savers are the factory tires on alloy rims. They are light and optimised.
I keep a set for around town and Toyos on steel rims for off-roading.

[watsea Member Find all posts View Profile Close watsea]

Hi RRP and beerad,
Are you taking the rolling diameter of your AT wheels into account for your calculations?
How does the Prado work out the fuel usage? Does it use the revolutions and wheel diameter of the factory wheel for the odometer, or something else?
Maybe a correction for the wheel diameter may give you a better fuel usage figure.

For myself with a 2019 2.8L GXL, Toyota Bullbar, "aero" roof bars, and still with factory tyres. I regularly drive from Brisbane to Gold Coast for recreational scuba diving. Typically two adults with about 120kg of gear, the fuel usage is typically 8.0 L/100km for a trip that includes freeway and having a bit of suburban roads.

During March just gone, we headed to WA from Brisbane and back, about 11,500k. The Prado was close to its GVM while towing a caravan at ATM about 2.6 tonnes.
Unfortunately we encountered Westerlies for the majority of the journey towards the west, and Easterlies for the majority of return trip back to the east.
Fuel usage was calculated by tank fills at the pumps and odometer readings.
Usage while towing varied 17 - 21 L/100km

One afternoon, though, with a flat road and tail wind for a couple of hours, the dashboard display gave usage as 14.6L/100km.

Typically towing speed during the whole trip was 86-96km/hr. I still have not been able to adjust myself to drive at 2,000rpm in S4, that is about 80k/hr
Yes, I would like better fuel usage while towing.

[rascal Member Find all posts View Profile Close rascal]

Comparing one cars non towing figure to another cars towing figures isn’t that useful, as trailers cause more drag than just the weight increase.

I’d suggest your bad fuel figures would be due to three factors.
one, tyres. BFG 33s are big and heavy and take a lot extra to turn. As mentioned above though , don’t forget to adjust odometer readings by the OD %
two, roof rack. This is a killer for aerodynamics, and you will notice it much more on the highway than around town, as drag increases exponentially to speed . If possible move the stuff on the roof rack into the trailer and remove the rack. Fuel economy will improve quite a lot doing this.
three, auto behaviour. Consider getting a lockup kit for your auto. This will stop the auto slipping all the time up hills, etc. which really chews the juice, and enable you to run a higher gear rather than have to use 4th all the time.

fwiw, I have a V6 150 (supposedly terrible for fuel if I listen to the diesel owners ) with 3” lift, 265/70 BFGs, bullbar, raptor tune.(which changes auto lockup behaviour)
On highway (empty) it Consistently gets high 11s/100km. When towing my 2.4t enclosed trailer 2.4m wide, 2.4m high, 6m long with an all up combined weight of 4.7t I still get 17l/100 averaging 100-110 leaving it in drive rather than S.
without the tune so auto worked as factory, it was getting 22l/100 and I needed to use S all the time to stop auto overheating.
no such issues any more.

[beerad Lurker Find all posts View Profile Close beerad]

Thanks guys.

Yes comparing non-towing to towing is very different. I'm getting my statistics from ScanGuage2 with odometer adjustment to tyre size so it should be accurate.
I'm most likely going to down-size to 265/70 i think from 285/70 and hope to see 5-7L/100km difference when towing. I'll probably also look at a Steinbauer.

With the lockup kit? i'm fairly aware of the factory electronic torque convertor and also try keep it engaged by feathering the throttle up hills... it's a balance between engine temp (with TC locked) and then the auto-trans temp when TC is unlocked... gets to a point going up a hill if staying locked that the EGTs get pretty high, so best at that point to unlock TC and let it rev higher.

I'm assuming the lockup kit is a manual button? what are the benefits over the factory electronic TC?

[RPP Senior Member Find all posts View Profile Close RPP]

Hi Beerad, program your ScanGuage2 to display the Torque Converter Temperature.
When cruising undulating countryside you will immediately see when the lockup clutch lets go.
The Torque converter temps will rise well over 100C. Without towing I have seen mine over 120C.
You will also see and feel the effect of going to S4. More power and lower ATF temps.

[beerad Lurker Find all posts View Profile Close beerad]

Yes i run my ScanGuage2 with TCT temp, EGT, DPA (Diesel Particulate Cumulative %) and ATF (Auto-Trans).
When TC is locked Auto Trans and TCT temp are identical. Very easy to identify. S4 is definitely best for towing, any other gear setting the auto-trans temp continues to rise and rise above 120 - 135 before Prado auto-locks into 4th gear with TC locked... to ensure the temp drops. (note to everyone - use S4).