Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - coasting and average MPG

pherlopolus · 04-03-2011, 04:22 PM

I've been logging some data from Vag-com and i'm a bit confused how to work out average mpg...

I'm logging KMH and L/H, then in a spreadsheet dividing kmh by l/h to get KM/L, multiply by 2.82 to get IMP MPG.

all good so far

now when i get to a spot where I am in Neutral costing, my L/H drops to 0.39 (idle) and my Km/h stays high (say 100kmh for arguements sake) now my average is 100kml and my mpg is 282 (mmm tasty).

this alone throws the average out quite a lot!!!

BUT!!!

when i in gear coast, i get 100kmh at 0.00l/h (fuel cut off), which throws my MPG up in the infinity region (ok i get a div/0 error) even if i substitute a low value for L/H (0.0001) it's still a huge number. and my average goes incredibly high.

so for now i've been ignoring these 2 states, but how does everyone else (and more to the point cars with an average mpg display) work these out? do you get a max increment function, or is it clever stuff involving distance travelled vs fuel used over previous so many miles? (typing it out makes sense)

any ideas?

04-03-2011, 04:22 PM	#1 (permalink)
pherlopolus EcoModding Lurker Join Date: Mar 2011 Location: Telford UK Posts: 6 Big Red Bus - '99 Volkswagen Sharan TDI S 90 day: 41.53 mpg (US) Thanks: 0 Thanked 0 Times in 0 Posts	coasting and average MPG - confused I've been logging some data from Vag-com and i'm a bit confused how to work out average mpg... I'm logging KMH and L/H, then in a spreadsheet dividing kmh by l/h to get KM/L, multiply by 2.82 to get IMP MPG. all good so far now when i get to a spot where I am in Neutral costing, my L/H drops to 0.39 (idle) and my Km/h stays high (say 100kmh for arguements sake) now my average is 100kml and my mpg is 282 (mmm tasty). this alone throws the average out quite a lot!!! BUT!!! when i in gear coast, i get 100kmh at 0.00l/h (fuel cut off), which throws my MPG up in the infinity region (ok i get a div/0 error) even if i substitute a low value for L/H (0.0001) it's still a huge number. and my average goes incredibly high. so for now i've been ignoring these 2 states, but how does everyone else (and more to the point cars with an average mpg display) work these out? do you get a max increment function, or is it clever stuff involving distance travelled vs fuel used over previous so many miles? (typing it out makes sense) any ideas?