Heater off, too!
Created July 13, 2004, at 7:58 pm by Anonymous
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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7 years ago
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?
7 years ago
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
7 years ago
I have also noticed that when using the cruise control, the electric motor seems to be used more.
6 years ago
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.
6 years ago
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
6 years ago
Can anyone address how the AC performs on the
Prius in a desert climate? Information, please!
4 years ago
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!:)
4 years ago
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.
4 years ago
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.
4 years ago
As stated in the owners manual: The Prius gas engine runs continously when the engine is COLD. This wastes fuel and kills mileage, but is necessary. A gas engine must be at operating temperature or repeated starting and stopping will destroy the engine.
In cold weather, when you use the heater you are drawing heat FROM THE ENGINE!!! The Prius engine is equipped with a coolant storage tank. This is what your heater uses to warm the cabin when the engine is not running, or running at very low power settings. But when running the heater in cold weather you are cooling the engine coolant, and sooner or later then engine has to start and run continously in order to bring the engine back up to operating temperature.
The LESS you run the cabin heaters, the longer the engine stays at operating temperature (without running), and you get better mileage.
In the summer, the AC unit draws electrical power from the propulsion battery requiring the car to waste fuel to recharge the battery, and supply energy to the AC unit.
But before you shut off the AC... At expressway speeds, the aerodyamic drag from running 50+mph with the windows rolled down causes MORE lost power than running the AC unit. Especially in a very clean aerodynamic design like the Prius.
Bottom line: If you want the abosolute best mileage, use the heat & AC sparingly. Do you really need to drive a sauna in the winter? Or an ice box in the summer?
3 years ago
got a question....is there any reason to turn on a/c when u use the heater?
3 years ago
Cooling the air before heating it removes some of the humidity, which is the reason that windows fog up.
1 year ago
Before you get on your soapbox and tell everyone how stupid or lazy they are for not reading their owners manuals, perhaps you should research what you say BEFORE you say it. You kept saying dumb things like, "yada, yada, all electric, yada, yada" and "yada, yada, driven by electricity, yada, yada" and "yada, yada, no drag on the gas engine, yada, yada"... Do you think that a hybrid car is some sort of magic perpetual motion machine???? Gee, why don't they just put electric motors on the wheels and get rid of the gas engine altogether??? Do you think that they put some magic amount of "electricity" in the car when they build it to run the A/C, electric heater, lights and so forth? I suggest that you do a little re-reading of the science book you got in 7th grade - particularly the section about the 1st Law of Thermodynamics. I will paraphrase it for you in the same why that your 7th grade teacher did... "There is no such thing as a free lunch." Now, of course this, too, is obviously too complicated for you so I will dumb it down - but I'll let you find the error in your thinking by asking this question: Where do you think the "electricity" for the A/C and heater comes from???? Since you don't go to the GAS STATION and fill your tank with ELECTRICITY, do you think, that maybe, it comes from the gasoline that powers the engine that turns the generator (or the motor and is then regenerated by the brakes)? Maybe you should look at this article right here, on this site: http://www.hybridcars.com/gas-mileage-factors/airconditioning.html
Then you can save the righteous indignation for sometime when you actually do your homework.
1 year ago
Now that "dontlikeloudmouths" has proven he knows nothing about automotive technology, I'll post this for those who ACTUALLY have two working brain cells to rub together.
The Prius (and other parallel hybrids) achieve high mileage and fuel efficiency by running the gasoline engine INTERMITTENTLY and ONLY at highest efficiency throttle settings.
Gas engines are MOST fuel efficient when operating in the 60% to 85% load range. A gasoline engine operating at only 20% or 30% throttle gets HORRIBLE fuel efficiency.
The Prius runs it's gas engine intermittently to both drive the car AND recharge the battery. And while the gas engine is running, the engine runs within the 60-85% throttle range when possible. The constant velocity transmission allows the engine to run anywhere from 1200 rpm to 3600rpm while the car maintains a constant speed on the highway. By running engine rpm independent of the car's highway speed, the throttle setting can be maintained within the 60-85% range except at the lowest and highest horsepower settings.
When the Prius only needs a small amount of horsepower (cruising at city speeds) the gas engine is SHUT OFF, and the stored electricity in the battery drives the car.
By using ONLY a 60hp gas engine, combined with the electric system, the Prius has the performance of a 140hp vehicle, with the fuel efficiency of a 60 hp vehicle.
Am I going over your head "dontlikeloudmouths"? Do you need me to dumb these ideas down to your speed? How abut "Ugh- big motor bad, little motor good. Ughh, Ughh, Ughh".
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