View Single Post
Old 06-26-2012, 10:24 PM   #1 (permalink)
EcoModding Apprentice
Saskwatchian's Avatar
Join Date: Apr 2012
Location: Saskatchewan
Posts: 114

Eric's Explorer - '01 Ford Explorer Sport 4x4
90 day: 19.05 mpg (US)

E's V - '07 Nissan Versa SL
90 day: 33.11 mpg (US)
Thanks: 12
Thanked 25 Times in 18 Posts
What's your time worth? Fuel economy vs speed.

I thought I would post this here since it doesn't really fit elsewhere but I like punching numbers and think this might be interesting to some of you here.

I got a scangage on Friday and after some initial tinkering decided to see what kind of difference cruising speed really has on fuel economy.

Before the gage I would mostly cruise at 105km/h feeling it was a good compromise between getting where I am going in good time and saving fuel.

I reset the trip meter approximately every 100km on the open highway alternating between 100, 105 and 110km/h

for the 100km/h runs I got 10.1, 11.7, 11.2 and 10.4l/100km - average 10.9 l/100km
for the 105km/h runs I got 12.7, 11.3, 11.8 and 12.3 l/100km - average 12.0 l/100km
for the 110km/h runs I got 13.2, 11.9, 12.5, and 11.6 l/100km - average 12.3 l/100km

Using $20/hr and $1.25/l the net cost of going 105km/h over 100km/h for 100km was 52˘
Using the same numbers I was surprised to find that going 110km/h over 100km was basically a wash at -.5˘

I always figured going faster would have diminishing returns with fuel burnt trumping time saved. This is definitely not definitive in any way but interesting none the less. I am going to have to mix in a few hundred klicks of going 115 next time I go home and see how that works out.

The data was gathered on a trip from work to home for the weekend then up to La Ronge and back to work today. It is not a good controlled experiment but "psudo-random" I didn't use anything from the first 30km of driving or when I got close to a city where there was other traffic. Datums were from 90km to 125km long but mostly right around 100km. Roads were varied but I was surprised by the variance in readings despite the fairly long intervals. (I thought things would average out since there hasn’t been much wind and little elevation change.)

Anyway thought it was interesting. has anyone else here thought about having a "slow speed" and a "fast speed"? looks like my 105km/h compromise isn't really such a good idea after all.

  Reply With Quote