The 5,000+ mile average MPG thread
- Thread starter c1tro
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If you are adding manually the fuel then you are introducing another variable that is subject to bias (user, pump variability etc). I think for the purpose of this thread we should stick to the actual pics of the OCD - its more fun this way
Fuel pumps are calibrated and inspected by an independent body.
Your cars OBC is not.
There is no more accurate way to measure consumption than the old fashioned way of using fuel purchased and miles travelled.
Mine is the 4.6. 5.0 started in 2011. I do a fair bit of London commuting, 20mph type stuff. If I only commute to work, no cruising on A roads or Motorways, I get 12mpg.
Exactly this. Not that it bothers me, look at my mpg, it just seems odd to exclude what, 80+% of people for a rather silly reason.
Ah, ok, in which case the same gen engine but the smaller variant (updated the other post with more info - i don't drive a mustang). Official specs say it should still be more economical but crawling will kill the fuel economy, same issue with mine
Luckily I don't commute so it's either some stop start town driving or cruising at around 70-80 (eq).Doesn't the miles travelled result come from the OBC?
I dont disagree with you, I've just always wondered why the manual method is more accurate than the OBC considering you still have to rely on the OBC for mileage. And given most cars don't have 100% accurate speedometers (which I assume affects the OBC mileage), there's still room for error even when calculating manually. Or do these apps use GPS?
Good point about the mileage. It's doubtful an OBC is going to understand any misreporting of milage however, so the best way to check is probably to take your car on a simple drive and compare mileage on the dash to a GPS unit. Then at least you can add that variation into the mpg calculations when doing it manually. I may try that at some point, but that said my speedo is pretty much bang on speed given by GPS so I'll assume the odometer is pretty accurate, at least for my car.
Soldato
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Thought I'd add this as it's just cracked 75k logged, my speedo is pretty accurate too.
I like the idea that the ECU guessing fuel from injector duty is more accurate than a regulated pump delivering 50L of fuel!
As with every device or instrument fuel pumps also have a margin of error so they can't be 100% accurate and of you are filling up in different petrol stations you also have the inter CV to consider.
It's still more accurate than an onboard computer!
I've relayed this story before, but as it's probably relevant.
For a while I was travelling around 40 miles each way for work. The start of the journey from home was ~3 miles of fairly clear slow driving, followed by ~18 miles of free flowing motorway, before hitting ~ 3 miles of crawling motorway (road works).
At the point I would hit the crawling motorway bit, my OBC would report ~45mpg. During the crawling motorway traffic, trundling along at engine idle speed in 2nd, the 'instant' mpg figure would be up in the 70s. During this 3 mile stretch the journey average MPG would get up to about 60mpg.
That's not mathematically possible since my first ~ 21 miles would have used about 0.47 gallons of fuel (@45mpg), so the next 3 miles would have needed to use a negative amount of fuel to hit 60mpg (0.4 gallons for the 24 mile mark).
The trip computer was actually averaging out it's journey MPG figure over time. Which is obviously nonsense.
For a while I was travelling around 40 miles each way for work. The start of the journey from home was ~3 miles of fairly clear slow driving, followed by ~18 miles of free flowing motorway, before hitting ~ 3 miles of crawling motorway (road works).
At the point I would hit the crawling motorway bit, my OBC would report ~45mpg. During the crawling motorway traffic, trundling along at engine idle speed in 2nd, the 'instant' mpg figure would be up in the 70s. During this 3 mile stretch the journey average MPG would get up to about 60mpg.
That's not mathematically possible since my first ~ 21 miles would have used about 0.47 gallons of fuel (@45mpg), so the next 3 miles would have needed to use a negative amount of fuel to hit 60mpg (0.4 gallons for the 24 mile mark).
The trip computer was actually averaging out it's journey MPG figure over time. Which is obviously nonsense.
Tell us more about how inaccurate a very heavily regulated and regularly inspected pump is?
By comparison an OBC will be miles out, especially when not even comparing within marque!
It can be done!
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