Bad mileage myth?

[tripp]

Originally posted by DocVijay@Mar 13 2006, 08:02 AM
When you consider that and that I could NOT get below 40 mpg by driving at extremely high speeds and always at full throttle acceleration, I don't understand how people are getting dismal mileage.

Anyway, that's just my experience.

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It's baffling ain't it? I'd really like to go on a ride-along with someones who's in the low thirties or high twenty's. It would be really interesting to see what factors could lead to such low numbers.

[nerfer]

Originally posted by DocVijay@Mar 13 2006, 09:02 AM

Before the swap I was averaging 52 mpg on my daily 120 mile commute. After, I dropped down to aroud 42 mpg, but that was entirely due to my much higher average speeds (80 mph+) and aggressive driving style.
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When you consider that and that I could NOT get below 40 mpg by driving at extremely high speeds and always at full throttle acceleration, I don't understand how people are getting dismal mileage.

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I think you answered your own question without realizing it. "Daily 120 mile commute".
How many people do that? I drive 7.5 miles each way, and the first third I get about 25 mpg. Then the engine is warm and I get 50 or better the rest of the way, but so far it averages in the low 40's. Add a couple short drives in town over the weekend and it can easily drop below 40. And this is despite the fact that I drive conservatively, on a mixed suburban route with occasional stops, but not a lot of traffic tailgating me (so I can practice the P&G on the low rolling hills) and no >55 mph stretches.

But two other things I should mention. I bought my car last month, so it isn't broken in yet, and so far the temperature is in the low 30's during the day and mid 20's at night (Fahrenheit). I imagine after the first oil change and the warm weather that started last week it should be improving noticeably. And a longer commute would help my mileage claim, altho I would just end up burning more gas.

nerfer

[DocVijay]

Wow, lot's of responses. Yes, I admit that my long commute does infact help quite a bit in getting good numbers. However, a good portion of hte morning half or my commute is severe stop and go driving, with traffic rarely getting over 20 mph. If the weight of the wheels had that much of an effect, this part of the driving would greatly decrease my mileage. In this situation, if I drove to maximize the hybrid properties, I would try and exclusively use electric power, but if I were to do so, I would lag behind greatly when traffic makes it's momentary spurts of motion. With this traffic, I would have 50 other cars jump into the space left by using electric only. Becuase of this I pretty much always use a good amount of throttle to stay close enough to the car in front. This also should hurt my mileage quite a bit due to the heavier wheels.

But it doesn't. My drive home usually takes me about an hour. The drive in the morning usually take two. Same drive, but significantly more traffic in the morning, yet I was still able to get 49-51 mpg either way.

So for me the long drive is obviously a factor in the good numbers, but I have other factors that shold greatly reduce them as well.
-stop and go traffic vs. wheel weight
-wider tires and great rolling resistance
-less than economical driving style

So I'll say it again. I find it hard to believe that people are getting such bad mileage. If I can drive 70 miles at an average speed of 80-85 mph, and still not get below 40 mpg... Now I understand that cold temps, hills/mountains, short trips and so on can reduce numbers. But I also make short trips all the time. The gorcery store, my kids daycare, and many other things are all within 5 miles of my house. I make plenty of short trips with a cold engine. But I still get good mileage.

I agree with tripp and would like to do a ride along with some of these people getting such low numbers.

Oh, here's a pic of my dsiplay after the drive yesterday.

[Betelgeuse]

I see bit of information on your MFD that, in my mind, explains it all.

Outside Temp. 84F

Living in a moderately cold climate, I can say that I've been AMAZED at how much better my mileage has gotten in the past couple days (when it's been somewhat warmer).

[brasche]

I too drive regulary 80 mph and am averaging 46.5 overall. Along with warm Florida temps, I credit following others at a moderate distance for at least 5 mpg at 80 mph.

My question is, Why Toyota didn't include ave speed next to ave mpg?

[finman]

I have a similar MFD photo showing 50+ MPG...for 4 months during summer! Have to agree with the temp being a MAJOR factor. Even going downhill here when it's 10 degrees F, I rarely see 50 MPG.

Must move south....must move south...

[gschoen]

Originally posted by DocVijay@Mar 14 2006, 11:29 AM
The gorcery store, my kids daycare, and many other things are all within 5 miles of my house. I make plenty of short trips with a cold engine. But I still get good mileage.

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You call 5 miles a short trip, I call a short trip 1 mile. In the congested big-city Northside of Chicago, everything is close. I drive to Target, the grocery store and dry cleaners since it's hard to carry big & heavy things. The colder it gets in the winter, the more likely I am to drive a short distance. A double whammy ! - more short trips and colder weather.

While it doesn't happen too often, I've had a few tanks in the 37-39MPG range. Overall, my lifetime average is about 45MPG, mostly because an occassional road trip carries more mileage "weight" - lots of miles in one trip vs. lots of trips with low miles.

In short, it's entirely possible to get less than 40MPG. If you're baffled, make a road trip to Chicago, maybe Boston or NYC, and make some short drives around town. Your experiences may be different, that doesn't make others' less believable.

[DocVijay]

Originally posted by Betelgeuse@Mar 14 2006, 11:45 AM
I see bit of information on your MFD that, in my mind, explains it all.

Outside Temp. 84F

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I doubt that the temperature is the only thing giving me better mileage. Even when it was 40 degrees colder, I was still getting well above 45 mpg on the same drive, with temp being the only change. The temp caused maybe a 10% change in mileage.

However, even on the coldest days (often below 40 degrees when I'd leave in the morning, lowest was 26 degrees), I still never dropped as low as others are claiming. It has always been above 40 mpg, even at it's coldest and at my most inefficient driving. Cold temps will affect mileage in any car, not just a Prius, but it does seem to affect them more than others. Also, a block heater shold then mitigate most of the cold weather effects if that were the case.

Also, at what point does the benefit from increased temps diminish? At 90 degrees, at 100 degrees? Should I expect another 5 mpg once it gets to be 95 degrees every day? Probably not, but it's be nice.

Temperature is a factor, moreso than in other cars, but I don't think that alone will get you into the upper 20's for mileage.

[DaveinOlyWA]

temperatures play a HUGE part as long as AC is not used. the higher the temps. the better the mileage. i have tons of data on this.

[tripp]

Originally posted by DocVijay@Mar 14 2006, 01:29 PM
I doubt that the temperature is the only thing giving me better mileage. Even when it was 40 degrees colder, I was still getting well above 45 mpg on the same drive, with temp being the only change. The temp caused maybe a 10% change in mileage.

However, even on the coldest days (often below 40 degrees when I'd leave in the morning, lowest was 26 degrees), I still never dropped as low as others are claiming. It has always been above 40 mpg, even at it's coldest and at my most inefficient driving. Cold temps will affect mileage in any car, not just a Prius, but it does seem to affect them more than others. Also, a block heater shold then mitigate most of the cold weather effects if that were the case.

Also, at what point does the benefit from increased temps diminish? At 90 degrees, at 100 degrees? Should I expect another 5 mpg once it gets to be 95 degrees every day? Probably not, but it's be nice.

Temperature is a factor, moreso than in other cars, but I don't think that alone will get you into the upper 20's for mileage.

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Well, Doc, the other thing that I would imagine that you've got going for you is FL flatness. Your car can more easily maintain your target speed with fewer kWs. That allows you to have long periods of uninterrupted 50+ MPG. I bet that's more important than the temps (as you mention also).