Keys for city economy versus freeway economy

Discussion in 'Fuel Economy' started by some_other_dave, May 20, 2014.

  1. yaris12

    yaris12 Member

    Two weeks ago was the first time I averaged over 52 mpg (usually 48 mpg) going to and from work. I didn't have to stop anywhere before or after work. No A/C, dry roads, 45 psi tire pressure, weather in mid 70s, and schools were done for the year.
  2. yaris12

    yaris12 Member

    For me Freeway driving in the morning uses more gas than afternoon. Car sits outside at work during the afternoon and so it warms up quicker and high speed idle isn't on as long
  3. RedylC94

    RedylC94 Well-Known Member

    I believe you once reported 42.5 without, and 38 with AC at 60 mph. A more useful way to express the cost of AC might be in terms of gallons per hour (or $/hr). That example works out to about 0.17 gallons/hour.
  4. ALS

    ALS Super Moderator Staff Member

    So based on those numbers and local price of gas it would work out to 65 cents per hour to stay cool. :cool:
  5. WriConsult

    WriConsult Super Moderator

    I would agree on all 3 of these, but I think the importance of #3 and the ease of improving it hasn't been emphasized enough.

    When I'm driving in local conditions, I find that if I'm doing things right I'm only driving with my foot on the gas and the transmission in gear about 10-15% of the time.

    The rest of the time I'm coasting in neutral, or stopped. Pulse and glide makes a HUGE difference in the city. Get the maximum efficiency out of that overpowered engine for brief bursts, and avoid using it the rest of the time. It helps incrementally to kill the engine while you're coasting, sure, but ICE-on coasting is a bigger savings versus just driving down the road at a steady 25mph with the car in gear, than ICE-off coasting is vs ICE-on coasting.

    So the more I think about it, I'd argue that suboptimal engine efficiency is probably actually #2 in light to moderate traffic, with idling #3. Only in heavier traffic does idling rise to #2, or even #1 in major congestion.
  6. jcp123

    jcp123 Caliente!

    ICE on coasting is unavoidable sometimes, like my non-flat-towable slush box Echo. ICE on coasting is my best friend!
  7. RedylC94

    RedylC94 Well-Known Member


    I agree with your latest post. I didn't attempt to rank those three "killers" in order of importance---merely in sort of random order, considering that the rank varies with conditions and technique.

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