recent economy figures = good!

[wilsy7]

hey all, just thought id post this as it seems to go against the general views on the over optimistic trip computer, on the last two occasions will puting in fuel ive fill to the pump clicks, take the readings and go about my business.

the past two occasions the figures have been as follows,

21.99 litres of uel put in, 21.99x0.22= 4.83 gallons,

238miles divided by the 4.83 gallons = 49mpg

on this occasion the trip computer read 41mpg over the 238miles as compared to an actual 49mpg.

on the second occasion, 16.44 litres of fuel was added, 16.44x0.22= 3.61 gallons,

162 miles divied into the gallons = 44mpg

on this occasion, the trip read 39mpg.

i have checked that im am calculating correctly on fuel sites and they match up, id just like to know why the trip is well under what im actually doing rather than being over like it usually is. my only idea is that because i do alot of warming up and warming the car down the mpg takes a plunge before i even set off and as a results the trip mpg is always harder to get up rather than say resetting when driving as it goes down much easier.

anyone else of similar experience?

jordan

[Ad Lav]

Its 4.54 for the sum...

238 divide by 21.99 litres = 10.823 x 4.54 = 49.1

You do it the hard way lol

Edited 22 February, 2011 by Ad Lav

[wilsy7]

well i just used 0.22 as an esitimate insted of using like 12 decimal places, just to simplify things.

same thing lol

i have no idea what way you have just done it lol

Edited 22 February, 2011 by wilsy7

[Ad Lav]

lol I got a bit confused, both work the same!

I use 4.54 as that's how many litres in a gallon?

[wilsy7]

lol I got a bit confused, both work the same!

I use 4.54 as that's how many litres in a gallon?

right get ya now

thanks, that will work in future now and save a bit of farting about lol

[Ad Lav]

[Benatron]

Don't hate me for being pedantic but it is 4.546 litres to the gallon (4.55 if you are rounding to 2 decimal places).

Which does improve your economy figures!!

The trip only performs a best guess - if you normally do a lot of 10 mile journeys and then start doing 100 mile cruises on the motorway you will find that although it may show the same achieved MPG one will be up and one will be down - my SDI is usually 10% optimistic but on a 300 mile trip it will only be out by a couple.

[Ad Lav]

lol, I knew of the odd decimal place

[TeebsVRS]

I have always used 4.546 too. We are sad! :|

[wilsy7]

some people eh! lol :p