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Discussion Starter #1
My Mother-In-Law drove the Prius for about 300 miles today. I noticed that she averaged 40 mpg. Generally we were getting about 45 mpg. We're currently on vacation and it was wet today. Now here are the possible reasons I've come up with for this drop:

a) It was wet. Could this effect mpg?
b) My mother-in-law doesnt drive as efficiently?
c) It is colder here (about 45F) than the temp we regularly drive in?
d) There was an extra (not really heavy!) person in the car?!!!

Or could it be all of the above? The trip was 2x150 mile legs on the highway. Just curious if anyone knows...! :D
 

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Here is my experience with your questions.

A. Never had any difference unless your running the defroster, this runs the AC which of course will lower mileage.

B. This could be part of mileage cut. If stomping on the gas and driving over about 70 mph, this will reduce mileage. Was there headwind?

C. What was the temp? I have only noticed a 3 mpg drop from a temp of 50 deg, to a temp of 20 deg. I am still averaging 52mpg in the 20 deg.

D. I notice when I have a passenger in the car I loose 1 to 2 mpg on the round trip. But on a long trip of over 300 miles, there was really no difference. And this was on Interstate driving at no more then 65 mph. I also have had all the kids in the car. total of all of us would be about 630 LBS. I noticed again the 1 to 2 mpg difference.

I dont understand why your only getting 40 to 45 mpg. Are the majority of your trips less then 15 minutes long? (Other then this longer trip you have spoke of) This will also greatly reduce mileage. As the longer the car runs the more time it has to keep the optimal heating it requires to get the best mileage. You should notice this greatly in the summer time. I average 56 to 60 in 80 to 100 degree heat.

Also make sure your using 87 octane on your gas. anything less will only get you the same lower mileage results. I tried a tank of 85 octane gas, and I could almost watch the gas meter fall. Performance seems the same, but the mileage was almost 4-5 mpg less. Havent tried 91 octane yet, but probably wont due to some posts I have seen that the gas runs the car to rich or something to that nature. So I stick to the 87.

A few other factors maybe, if your using cruise control or not, and also if your using the climate controls AUTO setting to allow the computer to decide how the car runs at its best, while keeping you happy while driving. Do you have any addons like ski racks or bike racks that change the aerodynamics of the car. Or even some have wanted to pull trailers with their car.

Hope this helps
 

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Discussion Starter #4
A. Never had any difference unless your running the defroster, this runs the AC which of course will lower mileage.

Yes, the defroster was running constantly. In addition, the heater was running periodically.

B. This could be part of mileage cut. If stomping on the gas and driving over about 70 mph, this will reduce mileage. Was there headwind?

Yep, she does drive a little 'faster' than the average driver :D

C. What was the temp? I have only noticed a 3 mpg drop from a temp of 50 deg, to a temp of 20 deg. I am still averaging 52mpg in the 20 deg.

The temperature was about 40F.

D. I notice when I have a passenger in the car I loose 1 to 2 mpg on the round trip. But on a long trip of over 300 miles, there was really no difference. And this was on Interstate driving at no more then 65 mph. I also have had all the kids in the car. total of all of us would be about 630 LBS. I noticed again the 1 to 2 mpg difference.

Yes, two passengers.

I dont understand why your only getting 40 to 45 mpg. Are the majority of your trips less then 15 minutes long? (Other then this longer trip you have spoke of) This will also greatly reduce mileage. As the longer the car runs the more time it has to keep the optimal heating it requires to get the best mileage. You should notice this greatly in the summer time. I average 56 to 60 in 80 to 100 degree heat.

I haven't driven the car for long. It only has about 2000 miles on the clock so possibly it needs to be 'worn in' more? We do a lot of travelling of 15 minutes or less. Inflating the tires to 42/40 has improved the mileage. And we have never really driven the car for any length of time with NO luggage. Maybe its that low because we have had a sizable amount of luggage when we drive? Anyway, we'll see how it does over time.

A few other factors maybe, if your using cruise control or not, and also if your using the climate controls AUTO setting to allow the computer to decide how the car runs at its best, while keeping you happy while driving. Do you have any addons like ski racks or bike racks that change the aerodynamics of the car. Or even some have wanted to pull trailers with their car.

How much does cruise control get? I haven't really used it much yet. We don't have any racks or addons though we have travelled heavily laden which I spoke of earlier.

Thanks for the help.
 

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One other possible MPG drop that hasn't been mentioned:

Don't drive around in the "B" gear unless you have to! The 'B' gear will definately slow you down (less coasting), which will give you lower MPG.

personally, I think it's the different driver/driving style that is your culprit. My husband has a habit of driving at least 5MPG better than I do, and I'm the Prius' primary driver!
 

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Discussion Starter #6
The dealer told us to switch to the 'B' mode whenever we see the turtle appearing on the dashboard, but that doesn't seem to make any sense because won't that decrease the battery recharging level with the regular braking?

On another topic, what constitutes 'good' driving practice? I tend to come to a rolling stop at a light, drive at around 65-75 mph, accelerate quite hard to start but brake slowly. What would be a good driving habit? I get about 45mpg.
 

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adeshell said:
A. Never had any difference unless your running the defroster, this runs the AC which of course will lower mileage.

Yes, the defroster was running constantly. In addition, the heater was running periodically.

B. This could be part of mileage cut. If stomping on the gas and driving over about 70 mph, this will reduce mileage. Was there headwind?

Yep, she does drive a little 'faster' than the average driver :D

C. What was the temp? I have only noticed a 3 mpg drop from a temp of 50 deg, to a temp of 20 deg. I am still averaging 52mpg in the 20 deg.

The temperature was about 40F.

D. I notice when I have a passenger in the car I loose 1 to 2 mpg on the round trip. But on a long trip of over 300 miles, there was really no difference. And this was on Interstate driving at no more then 65 mph. I also have had all the kids in the car. total of all of us would be about 630 LBS. I noticed again the 1 to 2 mpg difference.

Yes, two passengers.

I dont understand why your only getting 40 to 45 mpg. Are the majority of your trips less then 15 minutes long? (Other then this longer trip you have spoke of) This will also greatly reduce mileage. As the longer the car runs the more time it has to keep the optimal heating it requires to get the best mileage. You should notice this greatly in the summer time. I average 56 to 60 in 80 to 100 degree heat.

I haven't driven the car for long. It only has about 2000 miles on the clock so possibly it needs to be 'worn in' more? We do a lot of travelling of 15 minutes or less. Inflating the tires to 42/40 has improved the mileage. And we have never really driven the car for any length of time with NO luggage. Maybe its that low because we have had a sizable amount of luggage when we drive? Anyway, we'll see how it does over time.

A few other factors maybe, if your using cruise control or not, and also if your using the climate controls AUTO setting to allow the computer to decide how the car runs at its best, while keeping you happy while driving. Do you have any addons like ski racks or bike racks that change the aerodynamics of the car. Or even some have wanted to pull trailers with their car.

How much does cruise control get? I haven't really used it much yet. We don't have any racks or addons though we have travelled heavily laden which I spoke of earlier.

Thanks for the help.


As for tire pressure I run 47 in the front and 45 in the rears. Helps quite a bit, only thing is you will notice a little road walking on the highway.

Stomping on the accelerator will drop mileage. Gradually start when leaving a stop. Of course keep in mind the people behind you. Dont want to be too slow. But then if its me and where I live it doesnt matter how fast I start out, never fast enough for the person behind you. Try to cruise at 41mph or less and let off the gas and watch your meter, then slightly apply your foot on the gas again. This will run you in "Stealth" mode longer and up your mileage. Anything faster then 42 will run the gas engine. OF course like you said, you run the defroster all the time, this alone will run the gas engine causing lower gas mileage. Use your AUTO setting, and if the windows fog up make sure you switch to fresh air instead of re-circulate. I use this all the time and never use the defroster. The fresh air always takes away the inside foggy windows for me but lets in the other cars fumes from the road, making me gag.

The cruise at low speeds helps the engine run on battery power better then using your own foot. (like I said less then 41 mph). If all else fails, then maybe if your still having bad gas mileage problems and you have followed all of our advise. Try talking to your service rep. Have them check your computer and such. Could be your computer is a little on the lazy side. LOL. (could be the problem)

Also the more you break in the car you will notice better mileage. I have also noticed this has to do with how you breake it in. I think if you start out breaking it in the best way it will maximized mileage better in the future, then it will get this maximum mileage a lot better through the life of the car. But this is just my opinion. From the start I have always believed in this or I just got lucky and bought a car that is built very well and gets me better mileage. I think by this summer I will be around 60+ mpg since the car will be fully broke in by then.

Sorry to ramble, but just want to help. Good luck. Feel free to ask any further questions.
 

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driving style/tactics

I do city driving with my 2002 blue moon pearl. Many traffic lights and posted speeds of 30-35. I have found that for me to optimize my MPG, I need to get up to speed as quickly as possible so that I can "coast" in stealth mode for considerable distances. All bets off with AC on, however. Try different styles and pay attention to the results. The learning curve can be a long one! :)
 
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