An Observation

Discussion in 'Gen 3 Prius Main Forum' started by Metalman, Feb 24, 2011.

  1. Metalman

    Metalman Member

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    I made a couple of interesting (at least to me) observations recently. After filling the tank in Fort Myers, FL, I headed north on I-75 with the cruise control set to 64 mph. I was riding alone (240 pounds) with no luggage. The road is essentially flat and there was no appreciable wind and I was running the AC. By the time I exited the interstate, well over 100 miles north, the fuel mileage displayed almost 57 mpg. I don’t think I could have achieved such good fuel mileage without the use of cruise control, unless purposefully “glidingâ€. Also, the Prius maintained exactly 64 mph with the cruise control engaged.

    As I approached my destination, I was using the cruise control set to the 55 mph speed limit until reaching the reduced speed zone where I decelerated the CC to 40 mph. I switched the display to show the function of the engine, motor, and battery and saw that at 40 mph, there were only arrows moving from the battery to the motor to the drive wheels. The engine appeared to be off. When I slowed to about 20 mph, I switched to the EV mode and the Prius maintained battery power until I drove it into the garage at least a ¼ mile further. It appears that I traveled at least two miles without using the engine. My final mileage (indicated) for the nearly 200 miles was 58.7 mpg.

    I’m impressed.
     
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  2. eglmainz

    eglmainz New Member

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    I am also impressed, or there may be something wrong with the trip computer. In my experience, I have never been able to get a trip above 50mph to sustain an MPG above 50 with the Cruise Control set. I find that it tends to accelerate to hard in order to try to maintain speed.

    When I finesse the pedal, and work with it, I can manage that sort of MPG for this trip, and sometimes into the low 60s. But not using CC. It could be the slightly uneven terrain, but certainly not something to call hilly, as I do not think that there is 25 feet of elevaton on my 20 mile daily commute, including overpasses.
     
  3. revhigh

    revhigh MPG Enthusiast

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    I've easily done that every time I take an extended trip on the highway. I set cruise at about 62-64, set ECO mode ON, and I get right about 57-58 MPG indicated, and about 56 calculated. That's on a brand new engine and very cold temps as well.

    Cruise and ECO seems to be the best combination for me. I use cruise whenever possible. I've also said before ... the Prius has the best, most rock-solid cruise control that I've ever had in a car. It's VERY rare that it varies from what it's set at ... even by 1 MPH.

    REV
     
  4. eglmainz

    eglmainz New Member

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    Rev, this could be because I have a Prius V, with the 17 inch tires, and I know that they reduce the MPGs a little. I have been able to get that sort of mileage on CC with shorter trips, but never anything sustained.
     
  5. bisco

    bisco cookie crumbler

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