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Discussion Starter #1
Hi there has anyone else manually checked what the actual mpg they are getting compared to thefigure displayed by MAPS and More

Last tank 301 miles
25.5 litres
calculated as 54 and a bit mpg
MAPS and More showed 59 mpg?

Any thoughts?
 

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i shall be doing that with my next tank that i buy, but from what i can tell so far mine seems a tiny bit out compared to what the maps and more says as well. still pretty awesome tho compared to my old car
 

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Roadrunner said:
Last tank 301 miles
25.5 litres
calculated as 54 and a bit mpg
MAPS and More showed 59 mpg?
Kind of goofy that you're thinking in two different measuring systems to figure out your fuel economy.
 

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Roadrunner said:
Hi there has anyone else manually checked what the actual mpg they are getting compared to thefigure displayed by MAPS and More

Last tank 301 miles
25.5 litres
calculated as 54 and a bit mpg
MAPS and More showed 59 mpg?

Any thoughts?
I am seeing something similar. Had my suspicisions on the last fill up, but had not reset the long term counters. So have reset counters on last fill up and will report futherwhen i next fill up. But I also think it is about 4-5mpg out and cant understand how it can get the calculation wrong.
 

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My other car is a Lexus CT200h - a Prius in Lexus clothing. I'm a member of a mainly US based CT200h forum, and it is widely accepted that the CT200h tends to report mpg which is about 2-3 mpg more than you get if you divide the number of miles driven by the amount of petrol bought ( about 55 mpg as reported by the car as opposed to 53 mpg by distance/volume of petrol).

This value seems fairly constant as some of the owners have been keeping records for several thousands of miles. I get the impression it is widespread across the motor industry.
 

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Discussion Starter #8
My BMW120 diesel is pessimistic. The computer says 47 mpg and the car is actually doing 50mpg.
My previous cars with fuel computers, a Prius was pretty much spot on, and a Panda diesel, was similar to the UP.

I checked it because I won't to know how accurate the gauges are, so I know how much to rely on themEdited by: Roadrunner
 

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Discussion Starter #9
As to how it gets it wrong, it's probably find it difficult to measure the small quantities of fuel being used, as any error would be significant. As you use more fuel as in accelerator it probably gets more accurate, but hat would men driving I hard which defeats the object of having a small runaround
 

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The speedo & mileometer always have to read on the optimistic side so M&M will give amore miles pr. gallon than tank full to tank full.I get an average of app.4 to 5mpg. diff.
 

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philmar said:
The speedo & mileometer always have to read on the optimistic side so M&M will give amore miles pr. gallon than tank full to tank full.I get an average of app.4 to 5mpg. diff.
By law the speedo can overestimate, by I think 5%, and it makes sense. I don't think there is any requirement on the mileometer, although I assume changes to the tyres could lead to errors.
 

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Leif said:
By law the speedo can overestimate, by I think 5%, and it makes sense. I don't think there is any requirement on the mileometer, although I assume changes to the tyres could lead to errors.
Haven't had a chance to checkthe kph on my up! but my Lupo was always about 10% less than the displayed speed. They had some self check radar stations set up here in Switzerland. If it was an 80kph zone and I held the speedometer needle exactly at 80 the radar unit always said I was actually doing about 72 or 73kph, in a 60 zone I was doing about 54 or 55kph.



The question that always came to mind was, if my speedometer was displaying a speed that was 10% faster than what I was really traveling then was the distance measured10% farther thanthe vehicleactually traveled..??
 

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vwild1 said:
Leif said:
By law the speedo can overestimate, by I think 5%, and it makes sense. I don't think there is any requirement on the mileometer, although I assume changes to the tyres could lead to errors.
Haven't had a chance to checkthe kph on my up! but my Lupo was always about 10% less than the displayed speed. They had some self check radar stations set up here in Switzerland. If it was an 80kph zone and I held the speedometer needle exactly at 80 the radar unit always said I was actually doing about 72 or 73kph, in a 60 zone I was doing about 54 or 55kph.



The question that always came to mind was, if my speedometer was displaying a speed that was 10% faster than what I was really traveling then was the distance measured10% farther thanthe vehicleactually traveled..??
Obvious your laws differ from UK ones. I tested my speedo with a GPS unit, and the speedo overrread speeds. Actually I think it was 10%, not 5%. I've tested several cars, same result. I don't think the mileometer is coupled to the speedo, could be wrong. My simple tests suggest that it was reasonably accurate. I haven't tested my Up.
 

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Have we considered that the speedo/odometer may calculate speed and distance travelled by the number of rotations per second and total rotations of the wheels and may be calibrated to a particular circumference? Thus showing possible inaccuracies in speedo/odometer readingsbetween the 14/15/16 inch wheels offered on the up! if not calibrated correctly.


As above there isn't a necessity or legal requirementto have highly accurate readings for speedos/odometers so there will be a difference between indicated speed and true speed and presumably from indicated/true distance travelled.



Also that M&M may use a GPS odometer and the difference may just come from the crudeness of odometer/petrol pump measures against the high level of accuracy of a GPS odometer?



For some reason we stopped measuring seconds in elephants and mississippi's to!
 

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Ibelieve there is only one drive from the gearbox to the speedo so i think the error must must be in the mileometer as well as the speedo unless some sort of correction is applied.
 

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....and that's before we start on fuel pump accuracy, octane rating and fuel temperatures.


I'm just happy to see people posting good, high numbers which are a huge chunk better than my previous car.
 

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You can always check your speedo mph against the M & Mnavigation screen which is satellite monitored.Tank to tank I am averaging 50mpg which is exactly the same asmy Lupo TDi over the same ruraljourneys,this is based on the last 800 miles.
 

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philmar said:
Tank to tank I am averaging 50mpg which is exactly the same asmy Lupo TDi over the same ruraljourneys,this is based on the last 800 miles.

Which must be saving you ~35-40p a gallon just on fuel price differential petrol/diesel or around about £3 a tank?
 
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