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Best way to calculate MPG is to use your vehicle's Instant Fuel Consumption display.

I don't care which app you use, or if you write down how many gallons (or litters) you pump into your vehicle's fuel tank every time, nothing as accurate as your vehicle's instruments.

People don't understand fuel tank capacity varies with temperature, so your calculations are not as accurate as you think.

We build fuel trailers, on every trailer we always allow 2-3% expansion to make sure if we sell you a 10,000 litter trailer you will always load 10,000 liters into that tank, summer or winter, same for all other manufacturers.
 

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Best way to calculate MPG is to use your vehicle's Instant Fuel Consumption display.

I don't care which app you use, or if you write down how many gallons (or litters) you pump into your vehicle's fuel tank every time, nothing as accurate as your vehicle's instruments.

People don't understand fuel tank capacity varies with temperature, so your calculations are not as accurate as you think.

We build fuel trailers, on every trailer we always allow 2-3% expansion to make sure if we sell you a 10,000 litter trailer you will always load 10,000 liters into that tank, summer or winter, same for all other manufacturers.
This is very true for diesel. Gasoline expansion is fairly minimal.


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2019 Dodge Caravan 35th Anniversary Edition
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Thx. So would it be fair to say using the app calculation method, and assuming temperatures are varying, that we are off by 2-3%, or is it much more than that? Because I can live with 2-3% when we are talking mpg or l/100 km.
 

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Just the opposite here. My 2016 GC is noticeably better in power and fuel economy than my 2007 GC and 2002 GC were,
I have a 2004 with 110K miles that gets in the mid 20s for mileage in general. My new 2019 with 19k miles and similar driving habits hasn’t hit 20mpg yet. less power acceleration responsiveness. i don’t beat my cars. I keep them long term but this One is a disappointment.
 

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Thx. So would it be fair to say using the app calculation method, and assuming temperatures are varying, that we are off by 2-3%, or is it much more than that? Because I can live with 2-3% when we are talking mpg or l/100 km.
I don't see why you need to use an app when you already have a pretty accurate calculating system installed in your vehicle already.

If using an app for long time, temperature variations should not really matter,. Problem is, you have to manually key in the numbers at every fill up. Here is where discrepancies could affect your final numbers.

Problem with this method is, if you want to calculate MPG for one specific trip, filling up at the beginning of the trip and filling up at the end of the trip is not going to be accurate as the fuel tank may not hold same exact capacity both times.

Not all gas pumps are equipped with a vapour recovery system, so the pump might not automatically shut off at the same level every time.
 

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Save on gas with morning fill-ups? Don’t bet on it
Craig Eerkes, former chairman of the Petroleum Marketers Association of America, a trade group for filling stations, says that the expansion and contraction of gasoline due to day-long temperature shifts is, for the consumer, "Just so, so minuscule as to be almost nonexistent."

Judy Dugan, Research Director for the California advocacy group Consumer Watchdog, says, “The temperature variation between day and night at an individual gas station is apt to be negligible. She also notes that today’s double-welled tanks tend to keep the gasoline at the same temperature at which it’s deliver for a while. "If fuel is warm when it’s delivered to a station, it’ll still be warm when it’s sold a few hours later."
I typically get a 7% to 8% variation between calculated fuel consumption and EVIC display per fill-up. The EVIC display shows a lower fuel consumption. Interestingly, the 2002 GC and 2007 GC showed the same disparity between calculated and overhead display. Can't see that being due to volume differences.

I get 420 size propane tanks filled fairly often. There's a temperature/volume correction (to 15C) on that invoice.
 

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Save on gas with morning fill-ups? Don’t bet on it
I typically get a 7% to 8% variation between calculated fuel consumption and EVIC display per fill-up. The EVIC display shows a lower fuel consumption. Interestingly, the 2002 GC and 2007 GC showed the same disparity between calculated and overhead display.
And who are you going to believe, your vehicle's calculations or your calculations?

Your calculations?

Don’t bet on it
 

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And who are you going to believe, your vehicle's calculations or your calculations?

Your calculations?

Don’t bet on it
I believe my slide rule's calculations. :)
 
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And who are you going to believe, your vehicle's calculations or your calculations?

Your calculations?

Don’t bet on it
I have greater faith in the dollars leaving my pocket from a certified pump that measures the actual gallons. I still have to trust my vehicles’ odometer being correct.


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I have greater faith in the dollars leaving my pocket from a certified pump that measures the actual gallons. I still have to trust my vehicles’ odometer being correct.
You still have to rely on the odometer, so you might as well rely on all other sensors.
 

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You still have to rely on the odometer, so you might as well rely on all other sensors.
I always rely on the sensor that tells me to change the transmission fluid. :)

You know, if you spray the whole vehicle with Fluid Film, it will glide better through the air, give better fuel mileage and help rust protect the vehicles behind you. 🚓🚗🚙
 
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Best way to calculate MPG is to use your vehicle's Instant Fuel Consumption display.

I don't care which app you use, or if you write down how many gallons (or litters) you pump into your vehicle's fuel tank every time, nothing as accurate as your vehicle's instruments.

People don't understand fuel tank capacity varies with temperature, so your calculations are not as accurate as you think.

We build fuel trailers, on every trailer we always allow 2-3% expansion to make sure if we sell you a 10,000 litter trailer you will always load 10,000 liters into that tank, summer or winter, same for all other manufacturers.
You maybe right, but I don't have a fuel consumption display on my minivan. However my wife's dodge journey does. So I have to compute the old fashion way. My point being is that my T&C Minivan is 12yrs old, if I'm getting those kinds of miles than the car is doing well for 107,805 miles. I realize those numbers maybe off a little bit overall not bad.
I always rely on the sensor that tells me to change the transmission fluid. :)

You know, if you spray the whole vehicle with Fluid Film, it will glide better through the air, give better fuel mileage and help rust protect the vehicles behind you. 🚓🚗🚙
What sensor? I just change trans fluid every 60,000 miles.😳
 

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Its never come on and I had to change the gasket anyway.
I was just kidding with LEVY. There's no sensor BUT should be one, just for LEVY to say "pay attention to your sensors". :) The Owner Manual does have a fluid/filter change interval for the transmission.
 
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I took a trip on Saturday this last weekend from Woodland, WA to Doty, WA. I've wanted to go to Doty, WA for a long time just to check it out.

Doty, WA is a small town, I think the population is about 250 people. I think the nearest gas station is twenty miles to the east, and I don't know where there's a supermarket.

I left Woodland early in the afternoon, I never did look at the clock in my van, I tend to forget it has one, but it was bout 82 degrees out. I stopped at a couple street signs in Doty so I could photograph them, they said Doty on them. I drove around for a bit, maybe ten minutes, then headed home.

I think the drive was about 152 miles give or take, and I checked my fuel economy just north of Woodland and was happy to see a reading of 22mpg. Not bad for a van which has had the entire floor cut out and replaced with something heavier, had the rear end jacked up several inches, has a powered folding wheelchair ramp in it and was carrying my 175 pound bulk and the weight of my eighteen year old Blast 850 which weighs about 250 pounds. Actually my Blast 850 is a lot lighter than my 2013 Permobil C350, but the Permobil broke down a few weeks ago and I'm awaiting permission from my health insurance provider to have it repaired, a process that takes weeks.

So yay, 22mpg. My '86 Caravan LE gets 19mpg on road trips, and my '85 Ford Econoline gets 8mpg on road trips.
 
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