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  1. #1
    Guest

    Heater off, too!

    I have Toyota Prius and I recently have been doing some observing of my driving habits to see how I can get the best mileage. In addition to the tips already posted on this site, here's another one that got my mileage to 50mpg. Don't use the heater!! Pretty simple one, and hasn't caused me any great inconvenience. If I just turn the dial to the highest temp, but don't turn the fan on, I still get a little warmed up. And I still get good gas mileage (even with my car fully loaded for camping!!!). I hardly use AC so turning off the heat has really increased my mileage to about 5mpg more!!!

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  3. #2
    Guest

    Heater off, too!

    Well, it would make sense that when you turn off the a/c that your mpg would go up since the a/c does use more power from the engine. The heater though? I'm no automotive genius, but I would think that the heater would take very little power from the engine. If I'm correct, there is an a/c clutch that connects to the engine for the a/c to get power, where as when you turn on the heater a fan runs off ?electricy/a belt?...? I remember back in February and March of this year, my civic hybrid wasn't geting as good of gas mileage as it does now, which could be a result of three things:
    1. Your theory of using the heater causes less mpg.
    2. Since it takes longer for the engine to heat up in cold weather, I was using more gas as the auto-off feature would not turn on until the engine was fully heated up.
    3. Since my car was brand new at the time, it might have been getting less mpg than it is now due to it not being worn in.

    What do you think?

  4. #3
    Guest

    Heater off, too!

    i suspect your gas miles in the winter - when the car was new - is better now because the car is more broken in.

    there also seems to be a better gas mileage blend in our summer blend verses winter blend (at least in so cal).

    observing *better* gas milage with heater on verses off might be mistaking the heater as a reason while something else was involved. like windows rolled down more? different driving patterns when the weather is nicer?

    the idea that the engine auto-off feature not being active as fast in winter verses summer may be true.

    are there any of the hybrid engineers monitoring this site? some true answers would be nice.

    i wonder lately if the civic hybrid cruise control button - the one that accelerates the car - is hooked up to ONLY use the electric motor to accelerate and NOT use the gas as much. i never hear much of the actual engine when accelerating with this button verses the gas peddle.

    steve

  5. #4
    Guest

    Heater off, too!

    I have also noticed that when using the cruise control, the electric motor seems to be used more.

  6. #5
    Guest

    Heater off, too!

    I never drove our '02 Prius, until my husband died last summer. I chose to sell our Honda CRV, and keep the Prius. Over the fall months I was impressed with the MPG! But when winter came I thought that something had gone wrong with the car. I noticed that my MPG was around 27! Well here in Mn. I had to have my heater on at all times for winter driving, and I wondered if that was part of the reason for my low MPG. I also wondered if only having to drive the car mainly to work and back (just a few miles a day) is not enough to keep the batteries well charged. Well, last weekend I had to do a 220 mile road trip and since the temp. was mild I did not have to use the heater at all. I averaged about 47.9 mpg. So I guess nothing is wrong with the car and next winter maybe I'll put up with being less cozy, to get better milage.

  7. #6
    Guest

    Heater off, too!

    What GreenGirl has described is very much possible.

    The engine is at it's very worst MPG while cold and warming up.
    The heater core acts like a small radiator, and when you use the heater you are sharing the engine heat with the cabin heat. You can spend a considerable more time in warm up in this case.

    There was a few times in my past years of driving overheated clunkers when I used the heater set to hot and fan set to high to prevent a near-boiling cooling system from going over the edge.

    So much more for a tiny engine that is struggling to heat itself burning so little fuel.

    I commute 46 miles twice a day and kept it to cold for the first 10 miles, and kept it passive until 20.
    I live in the Atlanta Ga area so our winters are not that bad. Coldest last winter was about 22. (Brrr)
    If it takes ~20 miles to fully heat itself in these temps I can only imagine how long in the North.

    Also,
    Doesn't Prius have auxiliary electric heating?
    If this is also activated it's a double-whammy as more electricity is required. Whether this power comes directly from MG or drawn from the battery it must be paid back later from the ICE.

    Thanks,
    Steve
    2004 Honda Civic Hybrid
    Lifetime MPG is 60MPG

  8. #7
    Guest

    Heater off, too!

    Can anyone address how the AC performs on the
    Prius in a desert climate? Information, please!

  9. #8
    Junior Member
    Join Date
    Oct 2007
    Posts
    0

    Heater off too..............

    Turning off the A/C or heater has NO effect on mileage at all! The climate control system is ALL electric. There is NO DRAG on the gas engine at all since both the A/C and heat are driven by ELECTRIC motors, not the gas engine. In cold weather, the heat comes from an auxiliary tank of coolant that is heated by electric heaters until the gas engine warms up. Really, people, read your owner's manual, that thick book that comes with your car and explains everything. If you can't/won't read the manual, get to know your service people very well. Buy them a soda and ask a lot of questions. They are very knowledgeable and very helpful people. By the way, the power steering pump is also driven by ELECTRICITY, not the gas engine. Educate before you speculate!

  10. #9
    Junior Member
    Join Date
    Feb 2007
    Posts
    0

    Electrical Drain WILL hurt MPG

    About 90% of my drive is off-highway. I notice no difference in performance. As another user stated, this is because things like the heater, A/C, and headlights draw power off the battery. Not directly from the engine. However, I do notice a difference in mileage when using anything that draws additional electricity over regular driving. For those of us that drive city or roads with non-highway speeds, the decrease in mpg will feel greater. Since speeds are lower, the electricity gained from regenerative braking or the recharge from pulse will be less.

    There is a section of my drive where I travel a 3 mile stretch of level, low traffic road. Once I'm on that stretch, I put the cruise control to 35 mph and can go a little over 2 miles on electric mode before the engine kicks in to assist and recharge the battery. If I'm using the A/C, I might max 1 1/2 miles before the engine kicks in.

    For anyone that questions this, try this test. Coast down a big hill to max your battery. Let your Prius sit without using the A/C, heater, or headlights. Time how long it takes until the engine kicks in to recharge. Max your battery again, but this time let it sit with the A/C running. Your time until recharge will be considerably less. In my drives, I've notice that the heater hurts MPG very little, headlights a little more, and A/C the hurts the most. Figure this into your drive. Those of us with less of an opportunity in our drive to recharge the battery will be hit harder in the MPG.

  11. #10
    Junior Member
    Join Date
    Dec 2007
    Posts
    0
    Well, all of you are partially correct in that the climate controls do have a major influence on the mpg. But, in fact, it is the FAN that is the culprit here. Anytime you have an electric motor, you are getting the least efficient use of electricity out of an appliance, and that goes for any appliance. Your home heating/cooling system consumes a huge amount of electricity simply powering the fan necessary to distribute the heating/cooling. I live in Texas and we use AC the majority of the year down here. However, I routinely get 50+ mpg. How? By throttling down the fan to it's lowest setting, and only making adjustments to the temp as needed. Now when it's gettin' close to 100 outside, and I just jumped in my car, I do put the fan on high to clear out the heat as fast as possible. But after that, I put it on the lowest, or next to lowest fan setting, set the temp to a comfortable 72-75 deg, and let it go.

    And for winter, I'm still working on the solution to that. The heater seems to run constantly whenever the fan is on. And the a/c needs to be on or the windows fog. I'll let you know when that is worked out.

    Quote Originally Posted by GreenGirl View Post
    I have Toyota Prius and I recently have been doing some observing of my driving habits to see how I can get the best mileage. In addition to the tips already posted on this site, here's another one that got my mileage to 50mpg. Don't use the heater!! Pretty simple one, and hasn't caused me any great inconvenience. If I just turn the dial to the highest temp, but don't turn the fan on, I still get a little warmed up. And I still get good gas mileage (even with my car fully loaded for camping!!!). I hardly use AC so turning off the heat has really increased my mileage to about 5mpg more!!!

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