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Americas Why all the fuss about fuel economy?

I’ve got some roof rails to go on the front of my Alucab roof conversion. I’ll only use them when overlanding as no use for everyday at home.
One observation on fuel I’ve made though. I have the roof conversion, side awning, auxiliary fuel tank etc. so quite heavy and even less aerodynamic. On a regular 85 mile route of mainly motorway and dual carriageway, I get consistently over 20mpg [imperial] at a steady 60/62 mph. If I stick to 70mph then I’m around 16.9/17 mpg. Around a 15% increase in fuel use for an extra 10 mph that doesn’t get me there much quicker.
If you stick to driving at 155kph wherever possible you don’t dare look at fuel gauge. Just remember to fill up at every gas station. 😅 Joking aside, in namibia I averaged 17.3 MPG 13L/100km. Never looked at speedo. Just foot to the floor based on traffic and road conditions. Mostly 120-150kph. But slower in townships and rough roads. That was standard station wagon. No roof.

In Australia with a roof top tent on rough roads travelling at 80-100kph I average around 15.6MPG or 15L/100km.

PS both were diesel vehicles. Aussie one had Adblue. African one didn’t

Key lesson. Drive fast wherever possible. It seems to prefer it.
 
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It resets every night/extended period of inaction.
If you're describing the trip meter in the off road screen that also shows mileage and fuel economy during a period without several hours of inaction, then I agree with you completely. I was referring to the trip meter immediately next to the odometer. At least on my US spec 2024 Fieldmaster, absent the two apparent glitches that I mentioned, that does not reset following a period of extended inactivity. When I refill the tank, I select (if I'm remembering correctly -- it's intuitive at this point) the reset option that comes up from pushing the turn signal lever button the right way and that resets the trip meter next to the odometer to zero without changing the trip mileage on the off road screen.

The trip meter I am describing is the mileage shown in the lower right corner of this screenshot:

Screenshot from 2025-12-24 09-16-18.png

The off road trip meter (the one that automatically resets after inactivity but which doesn't change when I reset the regular trip meter following a fill up, at least on my vehicle) is this one:

Screenshot from 2025-12-24 09-21-12.png
 
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If you're describing the trip meter in the off road screen that also shows mileage and fuel economy during a period without several hours of inaction, then I agree with you completely. I was referring to the trip meter immediately next to the odometer. At least on my US spec 2024 Fieldmaster, absent the two apparent glitches that I mentioned, that does not reset following a period of extended inactivity. When I refill the tank, I select (if I'm remembering correctly -- it's intuitive at this point) the reset option that comes up from pushing the turn signal lever button the right way and that resets the trip meter next to the odometer to zero without changing the trip mileage on the off road screen.

The trip meter I am describing is the mileage shown in the lower right corner of this screenshot:

View attachment 7917205
The off road trip meter (the one that automatically resets after inactivity but which doesn't change when I reset the regular trip meter following a fill up, at least on my vehicle) is this one:

View attachment 7917207
If you press and hold it gives you the option of the 'daily' reset or the long term. You can choose either to show and reset.
Probably doesn't make a lot of sense but try holding the button at the end of the stalk to get a pop up then use, if i remember correctly, quick press to change the trip choice or long hold to reset. Either that or it's the rotary dial push up or down then click??

I'm sure i have confused things further, so if anyone else wants to step in with a better explanation 😅
 
If you press and hold it gives you the option of the 'daily' reset or the long term. You can choose either to show and reset.
Probably doesn't make a lot of sense but try holding the button at the end of the stalk to get a pop up then use, if i remember correctly, quick press to change the trip choice or long hold to reset. Either that or it's the rotary dial push up or down then click??

I'm sure i have confused things further, so if anyone else wants to step in with a better explanation 😅
That trip reset is so counter intuitive. I have never used it. As a result, I have never calculated by hand the actual MPG of the vehicle. I am sure Ineos did that by design, to obfuscate the real world fuel economy
 
That trip reset is so counter intuitive. I have never used it. As a result, I have never calculated by hand the actual MPG of the vehicle. I am sure Ineos did that by design, to obfuscate the real world fuel economy
So the conversation at INEOS went something like this . . .

“Let’s make a trip meter that shows MPG, but let’s also make it deceptive so that it shows 20 mpg when the actual mpg is 15. That’ll really trick our customers and increase profits.”

. . . which seems a little unlikely. A more likely explanation is an initial poor hardware / software implementation for our market that is a low priority for remedial action.
 
So the conversation at INEOS went something like this . . .

“Let’s make a trip meter that shows MPG, but let’s also make it deceptive so that it shows 20 mpg when the actual mpg is 15. That’ll really trick our customers and increase profits.”

. . . which seems a little unlikely. A more likely explanation is an initial poor hardware / software implementation for our market that is a low priority for remedial action.
I meant the poorly implemented trip counter
 
If you're describing the trip meter in the off road screen that also shows mileage and fuel economy during a period without several hours of inaction, then I agree with you completely. I was referring to the trip meter immediately next to the odometer. At least on my US spec 2024 Fieldmaster, absent the two apparent glitches that I mentioned, that does not reset following a period of extended inactivity. When I refill the tank, I select (if I'm remembering correctly -- it's intuitive at this point) the reset option that comes up from pushing the turn signal lever button the right way and that resets the trip meter next to the odometer to zero without changing the trip mileage on the off road screen.

The trip meter I am describing is the mileage shown in the lower right corner of this screenshot:

View attachment 7917205
The off road trip meter (the one that automatically resets after inactivity but which doesn't change when I reset the regular trip meter following a fill up, at least on my vehicle) is this one:

View attachment 7917207
I'm pretty sure you can control the behavior of both.
For the trip meter next to the odometer;
short-press to select the trip meter (if you're not seeing it, keep short pressing until it shows)
Long press to pull up the reset menu- Short press to select the reset schedule you'd like- long press to activate it

There's a procedure for the off-road menu too. I don't remember it. Mine is set to reset only when I reset it.

Then there's the paper fuel log in my center arm rest. It confirms that the Gren is calculating fuel mileage by not-US gallon. Long term calculation by my rig says 17.0 MPG. Paper log since day 1 says 15.1 MPG.
 
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