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Discussion Starter · #1 ·
I recently went on two trips totaling 255 miles.

I reset the trip quadrant values at start. As of now they read:

Miles: 255
Distance to empty: 153
Avg fuel (over the 255 miles) 37.5 mpg

This is telling me, if I understand correctly, that at 37.5 mpg I can figure on 408 miles for a 12.4 gallon tank.

Except there is a discrepancy:
37.5 mpg for 12.4 gallon tank = 465 miles. Now I did notice the total miles available (miles traveled + miles remaining) increase as my average fuel economy increased. So perhaps over the next 153 supposed miles to empty, I would actually get (465 calculated - 408 displayed = 57 miles) 207 miles (153 + 57). Assumption being that the vehicle stays at 37.5 mpg.

Likewise, something that looks approximately correct:
153 miles remaining at 37.5 mpg = 4.08 gallons remaining. The fuel gauge appears to be approximately 1/3 scale, but yes, that's really a guess. (4.08 remaining / 12.4 total) = 0.329 which is close to 1/3 tank remaining.

What are my Mk3 colleagues experiences with the calculated miles to empty values? Close? Way off? Conservative (i.e. 150 miles to empty, but really 180 'to be safe')? Aggressive? (i.e. says 150 miles to empty, you better not push past say 100)?
 

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Miles to empty is a fool's quest.
I have used the fuel low light for many years and it is a pretty good indicator that 2 gallons are left.

I have never used the miles to empty as it is too easy to abuse* and as others joke, telling your wife or kids to get out and keep pushing the car the last few 'miles to empty' HAS occured.

* the abuse is in your head, thinking you can always push it those last few miles... Maybe.. SURE!.. [hah] Ahhh I just ran out of gas five miles short, and I am mad... (At what? at yourself... 'cuz we TOLD you....)

Now if they only really DID make a 'World car" and have the bigger Euro 14 gallon tank in there...
 

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Discussion Starter · #5 ·
Miles to empty is a fool's quest.
I have used the fuel low light for many years and it is a pretty good indicator that 2 gallons are left.

I have never used the miles to empty as it is too easy to abuse* and as others joke, telling your wife or kids to get out and keep pushing the car the last few 'miles to empty' HAS occured.

* the abuse is in your head, thinking you can always push it those last few miles... Maybe.. SURE!.. [hah] Ahhh I just ran out of gas five miles short, and I am mad... (At what? at yourself... 'cuz we TOLD you....)

Now if they only really DID make a 'World car" and have the bigger Euro 14 gallon tank in there...
Interesting. I would then expect as soon as the low fuel lamp displays the miles to empty would predict (2 x avg fuel economy) miles remaining. Sounds like it doesn't. Don't think I'll get the chance, or want to take the chance to find out.
 

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Interesting. I would then expect as soon as the low fuel lamp displays the miles to empty would predict (2 x avg fuel economy) miles remaining. Sounds like it doesn't. Don't think I'll get the chance, or want to take the chance to find out.
I'm sure you remember the 1979 energy crisis and the odd-even gas rationing. Long lines at the gas station and the daily allotment was often sold out before noon. Rich people owned two cars with odd plates on one and even plates on the other so they could stay mobile. Even richer people actually had their back yards dug up and gas station size tanks buried underground for their own private fuel reserve.

Ever since then, I have never let my tank go below a quarter full before I start getting nervous and looking for a gas station.
 

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Trip computers can be entertaining if you're really bored, I enjoy the passing scenery more than figuring out their workings & how close to reality they may estimate.

To answer the question for your individual car, run it down near empty (warning light) then note the miles remaining and the gallons needed to fill it. That will give a better idea of how optimistic or conservative it is & how close to "empty" it will let you go.

True useable fuel numbers can only be determined by running it dry, not particularly good to do on purpose.

Miles to empty is based on a different number than the current tank's mpg as you noticed. Shorter term average is typical, some MkIII owners have noted this holds for them.

Any trip computer is "dumb", you can outguess it by knowledge of your normal average for different types of driving combined with the one thing it CAN'T know - what kind of driving you will be doing in the near future.
 

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"Distance to empty" is good for planning but is always changing relative to miles driven. It's nothing more than a best guess. As your current MPG changes, DTE updates at different rates -- from about one mile for every 2 miles driven to about 2 miles for every mile driven and is based on an algorithm of recent and historical miles driven. Theoretically if you always get the same mileage all the time it would get very close to estimating your actual miles to "empty".

So while never accurate, it makes an excellent estimating tool for refueling purposes, especially on trips. In such cases, if, for example you pick up a head wind, it reduces your remaining range taking into consideration the intensity and duration of the headwind based on its effect on your MPG. I use it all the time![cool]
 

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In my German Focus These values are "pretty" accurate. Not like i'd wanna drive it until the last mile regarding the "Miles to empty" Counter, but once I've been down to like "15 miles left" (starting to become very nervous)and the fuel tank was nearly dry, prolly less than a half gallon left. Don't really wanna challenge it since i don't have an emergency fuel canister in my trunk.
 

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I do on average 550 KM per tank. My average consumption is 7.50 L/100 KM for 550 KM. I will do 500 KM with 8.00 L/100 KM. Now, depending on the data on screen I can know when I will fall short. However, the data change. For example, you do the first 50% of the tank in city and after you do highway. Your L/100 will decrease on your last 50% because you consume way less.

I would suggest also to gas only when nearly empty and to always gas the same way: do not overflow or put half of a tank in there... keep it steady.
 

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Now if they only really DID make a 'World car" and have the bigger Euro 14 gallon tank in there...
This^^^^^^^^^^ I don't get the small tank. It needs at least a 14 gallon tank.
 

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Discussion Starter · #13 ·
Just out of curiosity, why did Ford change from the Mk1 and Mk2's 14 gallon tank to the Mk3's 12.4 gallon tank?
 

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Discussion Starter · #16 ·
1. MK3 mpg increased

but the real reason is

2. The US spec large evaporative emissions vapor canister sits on top of the fuel tank and takes up space. (The Euro model still gets the 14 gallon tank)
European (and Asian?) models don't implement EVAP?
 

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Discussion Starter · #17 ·
Guess I don't see the fuss with a 14 gallon tank; doesn't make a bit of sense to me. 12.4 gallons at 35 mpg gives us 434 mile range. Where exactly is one traveling that 434 miles between fills is too short of a distance?

If one wants F-250 diesel fuel range, then why doesn't one purchase an F-250?
 

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Guess I don't see the fuss with a 14 gallon tank; doesn't make a bit of sense to me. 12.4 gallons at 35 mpg gives us 434 mile range. Where exactly is one traveling that 434 miles between fills is too short of a distance?

If one wants F-250 diesel fuel range, then why doesn't one purchase an F-250?
Could be we already did the 350 Amarillo thing & have also done the 200 miles range on 5.0's. How many ppl are going to use the 35mpg for a DDer? More like 25-30mpg during the week.
 

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Discussion Starter · #19 ·
At 25 mpg, the 12.4 gives 310 miles. Maybe the best thing to do is put a 5 gallon fuel can in the trunk or hatch. That gives one an extra 125 miles for a grand total of 435 miles.

I can see where 310 miles is a hassle. You have to get out of the vehicle, walk to the right side of the vehicle, push open the fuel door, start/pay/commence the fueling operation, wait for the 12.4 gallons to dispense, stop the fueling operation, close the fuel door, possibly wait for the receipt to print... yeah it's a mess of unproductive time.
 

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At 25 mpg, the 12.4 gives 310 miles. Maybe the best thing to do is put a 5 gallon fuel can in the trunk or hatch. That gives one an extra 125 miles for a grand total of 435 miles.

I can see where 310 miles is a hassle. You have to get out of the vehicle, walk to the right side of the vehicle, push open the fuel door, start/pay/commence the fueling operation, wait for the 12.4 gallons to dispense, stop the fueling operation, close the fuel door, possibly wait for the receipt to print... yeah it's a mess of unproductive time.
Try that at 200 miles.^^^^^^^^^^& thats if you don't have to wait or deal w/ different times of the day to avoid the lines.
 
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