What is wrong with this economy calculation??

Hi,

I have an A3 TDI DSG, currently done 4800 miles and i'm *still* concerned about the economy..

I filled up the tank with BP Ultimate Diesel and reset the DIS and trip counter. I'm now due to fill up again ( DIS showing I have 5 miles range left ) and the trip counter is showing 485 miles, and the average MPG is showing 50.7 MPG.

Now, by my reckoning, if I have a 12 gallon tank and the DIS is showing an average of 50+MPG, then I should be seeing 600 miles out of a tank?

Am I missing something here? [img]/ubbthreads/images/graemlins/confused.gif[/img]

Help appreciated!!

Re: What is wrong with this economy calculation??

work it out manually.

fill up the tank, see how many litres you put in it.

divide the amount of litres by 4.54

then get the 485 miles(or whatever you had done since the last fill up) and divide it by the previous answer.

ie, last time i filled up after town driving i had done 399.6 miles, it took exactly 45 litres.

45 divided by 4.54 = 9.91 gallons

399.6 divided by 9.91 = 40.3 MPG

funnily enough teh DIS showed 40.8 mpg so i can assume its fairly accurate in my case.

work it out manually and see if its the same as the cars calculation.

Re: What is wrong with this economy calculation??

I want DIS lol. Can you retro fit it?

Re: What is wrong with this economy calculation??

joshua

It's a 12 gallon tank (ish) but you have about a 1 1/2 gallon reserve, so 10 1/2 gallon useable I think anyway. So like others have said you need to check it manually. Even so your getting good mileage. I've done 6000 miles and have got an overall ( since new ) average of 44.5mpg.

This is mix of city, motorway sort stuff. Oh and a bit of spirited fun. [img]/ubbthreads/images/graemlins/lol.gif[/img]

Re: What is wrong with this economy calculation??

No matter what I do and how ever many times I reset the DIS, number 2 always ends up at 44.5mpg.

Just took the dog to the caost today and after 80 odd miles of drving number 1 was at 56.2mpg.

I have owned 4 Audis and every car has always given me between Audis urban and combined figures, within 1 mpg. That is on the DIS but every DIS has always been a little optomistic too, by between 5 and 10%.

Re: What is wrong with this economy calculation??

[ QUOTE ]

funny you get more diesel in your A3 than my A4 avant Q, and yet i get more miles!

And i drive like a twat!!

[/ QUOTE ]

Kris

Probably not the best remark to say on a forum that you're trying to sell your car on [img]/ubbthreads/images/graemlins/bang.gif[/img]

Re: What is wrong with this economy calculation??

Dont care doesnt every one at some point,

Re: What is wrong with this economy calculation??

[ QUOTE ]

About this reserve tank, i never understood how it works. is it just that when the needle shows there's nothing in the tank, there's still the 1.5 gallons left? if so, surely we know that so really it doesn't work as a reserve ebcuase we'll say " it's ok i've still got the reserve tank".

am i chatting crap?

[/ QUOTE ]

Well, I meant when the red light for 'fill up now' comes on you will have another 1 1/2 gallon left in the tank. I think the DIS reports 0 miles when the red light comes on, and not when it thinks the reserve is about used up.

Re: What is wrong with this economy calculation??

[ QUOTE ]

funny you get more diesel in your A3 than my A4 avant Q, and yet i get more miles!

And i drive like a twat!!

[/ QUOTE ]

Good advert for selling your car matey, lol

Re: What is wrong with this economy calculation??

mentioned twice mate and i dont really want to sell it, my chick does!!!

as i said before- least im honest!!

Re: What is wrong with this economy calculation??

The only way to work out mpg properly is to do the following.

1) Fill the tank to the brim and reset the trip meter.

2) Drive as normal and let the tank almost empty.

3) Refill to the brim and record the amount of litres/gallons needed to fill the tank.(4.54 litres = 1 gallon) and the milage on the trip meter

4) Divide the miles by the number of gallons and you have your mpg.

I have an A6 and the DIS is routinely showing about 2-3 mpg to much.