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# Is it possible in any way to buy a mpg thing that tells you the mpg for your car ? watch

1. Hi

I really would like to know if there is anything that can be bought for a car without a standard mpg trip o meter, is there anything you can buy such as a tool that plugs into your car that can tell you what mpg you are getting ?

tar
2. As has been explained before, the only true measure of MPG is by recording your miles against litres of fuel at the pump. You can use a site like Fuelly to help you track your data. In-car MPG displays are only ever accurate to a degree.
3. (Original post by Nuffles)
As has been explained before, the only true measure of MPG is by recording your miles against litres of fuel at the pump. You can use a site like Fuelly to help you track your data. In-car MPG displays are only ever accurate to a degree.
Can I ask you something?

I drove at 60 mph driving 180 miles on motorway from full tank, afterwards I estimate it will take £13 to refill to brim ( 13 litres) so this = 62 mpg
I drove another 50 miles, this time around town and the gauge hit half way on fuel. it takes 22 litres from half way to brim, so I calculated again but did 230 miles from 22 litres and it is only showing 44mpg
Now if I continue driving urban until fuel light comes on it is usually another 200 miles from half way to light on. so that will be approx. 430 miles from full tank. working that out it comes to around 43 mpg from full tank, which is only 3 mpg more than I usually get from urban alone despite that long motorway trip driving 180 miles at 60 mph

How is it that the first 180 miles saw me get 62mpg ( 180 miles from £13) , then if I drive 50 miles more it drops from 62 to 44 mpg and if I wait till fuel light comes on then the mpg drops to 45mpg ?
4. (Original post by I love life)
Hi

I really would like to know if there is anything that can be bought for a car without a standard mpg trip o meter, is there anything you can buy such as a tool that plugs into your car that can tell you what mpg you are getting ?

tar
Your car probably has an OBD connector somewhere inside, which is used by garages for vehicle analytics. If you find where it is, you can get a Bluetooth adapter for it which communicates with an app on your phone to give you real time data about things like fuel efficiency.

Posted from TSR Mobile
5. (Original post by Arbolus)
Your car probably has an OBD connector somewhere inside, which is used by garages for vehicle analytics. If you find where it is, you can get a Bluetooth adapter for it which communicates with an app on your phone to give you real time data about things like fuel efficiency.

Posted from TSR Mobile
It does have an OBD connector
6. A cheaper way to do it is to just use an app like fuelio to record when you refuel. Obviously you will only get an average mpg rating but that is what is important anyway.
7. (Original post by Talon)
A cheaper way to do it is to just use an app like fuelio to record when you refuel. Obviously you will only get an average mpg rating but that is what is important anyway.
??
8. (Original post by I love life)
??
????

That is my way of hinting that some words might be helpful!
9. (Original post by Talon)
????

That is my way of hinting that some words might be helpful!
?????
10. (Original post by I love life)
?????
Is there any chance you are going to actually state a question instead of just typing question marks?
11. (Original post by Talon)
Is there any chance you are going to actually state a question instead of just typing question marks?
OK, here is a question for you, do you like my feet ?

12. (Original post by I love life)
OK, here is a question for you, do you like my feet ?

Yes, very sexual, but you appear to be wasting my time for no apparent reason.
13. (Original post by I love life)
Can I ask you something?

I drove at 60 mph driving 180 miles on motorway from full tank, afterwards I estimate it will take £13 to refill to brim ( 13 litres) so this = 62 mpg
I drove another 50 miles, this time around town and the gauge hit half way on fuel. it takes 22 litres from half way to brim, so I calculated again but did 230 miles from 22 litres and it is only showing 44mpg
Now if I continue driving urban until fuel light comes on it is usually another 200 miles from half way to light on. so that will be approx. 430 miles from full tank. working that out it comes to around 43 mpg from full tank, which is only 3 mpg more than I usually get from urban alone despite that long motorway trip driving 180 miles at 60 mph

How is it that the first 180 miles saw me get 62mpg ( 180 miles from £13) , then if I drive 50 miles more it drops from 62 to 44 mpg and if I wait till fuel light comes on then the mpg drops to 45mpg ?
Your fuel gauge is not accurate. It's incredibly unlikely that when it gets to half it means you've used 22litres of fuel. The only way to get a truly accurate economy figure is to brim the tank each time you want to make a measurement and use the litres consumed against trip mileage.

You've clogged up the forum with like ten posts about your fuel economy, when none of it is correct information because you've made your calculations based on random guesses off the fuel gauge. I've already told you at least twice how to measure economy correctly, but you've yet to take my advice.
14. (Original post by I love life)
OK, here is a question for you, do you like my feet ?

wtf
15. The MPG in my car is pretty accurate. Can be disappointingly accurate at times. Calculates distance travelled to remaining fuel volume, and you can change the settings to go into a little graph with the consumption levels over a specified time, or choose certain timeframes so you could for example check how you did overall on the first hour of the journey compared to the second hour.

I don't know of any aftermarket measurers.

I was just writing a big long paragraph about how one could do it, but now I've decided to delete that and put it into my "business ideas" book :P Thanks for this thread, I'm excited now!
16. A calculator or a pen and a piece of paper can be bought at any good newsagent, stationer or supermarket.
The brain to operate this equipment might be harder to come by...
17. (Original post by Nuffles)
As has been explained before, the only true measure of MPG is by recording your miles against litres of fuel at the pump. You can use a site like Fuelly to help you track your data. In-car MPG displays are only ever accurate to a degree.
Actually the in car fuel economy calculator can be highly accurate, as it uses fuel pressure and injector opening times to calculate the fuel consumption. The major inaccuracy in them will be the speed information. That also affects working it out using pump figures. The other factor when using the pump is the calibration of the pump's automatic cut-off. When I could be bothered using an app to calculate my fuel consumption it wasn't that uncommon to get a low MPG figure for a tank, then the next tank would be high - the intervening fill up was just with a pump that had a higher cut off pressure, so it put more fuel in the tank. Of course, it very quickly gets to the point of life being just too short to worry about it...

(Original post by Nuffles)
Your fuel gauge is not accurate. It's incredibly unlikely that when it gets to half it means you've used 22litres of fuel. The only way to get a truly accurate economy figure is to brim the tank each time you want to make a measurement and use the litres consumed against trip mileage.
Not trying to pick holes, but the gauge is pretty accurate, it's just low resolution. Certainly some (probably most, these days) designs of fuel sender I've seen are only capable of transmitting 8 discrete fuel levels, which is why the gauge tends to sit at 1/8th, 1/4 etc. and move relatively quickly between them. As you say, it makes it useless when trying to accurately calculate fuel consumption.
18. (Original post by CurlyBen)
Actually the in car fuel economy calculator can be highly accurate, as it uses fuel pressure and injector opening times to calculate the fuel consumption. The major inaccuracy in them will be the speed information. That also affects working it out using pump figures. The other factor when using the pump is the calibration of the pump's automatic cut-off. When I could be bothered using an app to calculate my fuel consumption it wasn't that uncommon to get a low MPG figure for a tank, then the next tank would be high - the intervening fill up was just with a pump that had a higher cut off pressure, so it put more fuel in the tank. Of course, it very quickly gets to the point of life being just too short to worry about it...

Not trying to pick holes, but the gauge is pretty accurate, it's just low resolution. Certainly some (probably most, these days) designs of fuel sender I've seen are only capable of transmitting 8 discrete fuel levels, which is why the gauge tends to sit at 1/8th, 1/4 etc. and move relatively quickly between them. As you say, it makes it useless when trying to accurately calculate fuel consumption.
More modern vehicles might well have more accurate economy readouts, but cars that are ~10 years old like most of us drive aren't so accurate, I've found. The reading my Passat gives me correlates pretty tightly with what I get out of Fuelly, but if there was a discrepancy I'd trust Fuelly over the car (or my inability to input numbers correctly :P )

It's hardly uncommon to get in a car an the first half of the tank seems to take forever, but then the needle drops like a stone once lower than half way. As with everything, once you know your car then it's easier to make educated estimations, and easier to know when something isn't right. I Love Life needs to fix his MAF before worrying about economy anyway, seeing as it's most likely not running optimally right now.
19. (Original post by Nuffles)
Your fuel gauge is not accurate. It's incredibly unlikely that when it gets to half it means you've used 22litres of fuel. The only way to get a truly accurate economy figure is to brim the tank each time you want to make a measurement and use the litres consumed against trip mileage.

You've clogged up the forum with like ten posts about your fuel economy, when none of it is correct information because you've made your calculations based on random guesses off the fuel gauge. I've already told you at least twice how to measure economy correctly, but you've yet to take my advice.
Your getting it wrong not me

I have filled my tank from empty several times, it takes 43 litres from when light comes on to fill it to the brim. I usually get 40 mpg urban driving of around 400 miles per tank from urban. I have made a note several times how many litres it takes from half way to light come on and it is 22 litres, that will be about another 200 miles.
It is at half way now and I have covered 230 miles ( with 180 of that being motorway at 60 mph) If I use the mpg calculator online it will tell me 230 miles from 22 litres = 45mpg, however go back 70 miles from when I did the motorway trip and it told me 180 miles from £13 = 62mpg.
if I had put £13 in that would have filled back to brim again.
In another 200 miles approx. my fuel light will come on after 430 miles, = 44 mpg. that means I only got 4 mpg more on motorway than I get urban.
however, if I was to refill it after driving the first 180 miles it would only have cost £13 and I would have saw 62mpg from my car

I do not have a device in my car that tells me my mpg, I use the online calculator, torquecars uk mpg, to figure it out.

I have wiring for MAF now which cost £50 just for the plug and about 7 inch of wire, it has 6 wires, I will go get an auto electrician to fit it for me, not brian
20. its called maths

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