Causes of LOW MPG Average?

[Hutchings]

Hello friends, I am a newbie here, so please be gentle with me... I have already gained a huge amount of information here and at with my wife's encouragment (ok, she made me post this) I have a MPG question.

We traded in our Suburban for our new Prius and have been simply amazed at how our fuel bill has drastically changed. We are equally impressed with the incredible mileage we have attained. However, Here is our observation. Once we fill up we reset the trip odometers ( A and B ), and as soon as we start driving again, the average MPG rating resets as well. The issue I think we are having is that the average MPG never has gone over 45.0 MPG. We notice it hovering around 44.7 - 44.9, only occasionally reaching the 45 MPG rating on the MFD. So, once I leave Costco, having reset the trip odo's , I find that even while on battery only, that I still can not quite get 'er up over 45MPG. We have no MODS (other than the reverse beep disable) and use the AC/AUTO function most of the time. We use our headlights full time and keep the cabin temp around 72 degrees. My wife and I challenge eachother who can drive the smoothest, in efforts to bring the average up, but to no avail. We do nice and easy starts, take advantage of regen braking and are very light footed. We have also tried to "glide" (I think thats what its called) when there is no comsumpsion fromeither the battery or the engine. We kind of glue ourselves to the MFD. In our quest for more MPG we also have noticed that the ICE seems to like to run, even when we don't think it had any reason to start.

We have done the actual math (gallons used vs miles traveled) and have come to the same conclusion, that we are simplynot getting the premimum mileage we think weshould be getting (and like most members here are getting). Am I doing something incorrectly or can someone advise me if this feeling is justified?

Just for kicks and giggles, we tried to run without the ac ( yikes-103 degrees here today ) or the headlights on and it did not seem to make any difference.

So far, 2600 miles, and nearly 3 happy months of ownership. Verypleased with the technology and can't wait for my daughter to start driving so I can buy her a Prius as well.

And finally...I am confused what is actually happening when on the MFD, the battery level turnes from blue to green? Humm....

Thanks in advance for your comments friends and looking forward to future participation in the groups.

Stephen

[slortz]

Welcome to the club!
45mpg is not too bad. I think one question is what is the average length of the trips you are taking. My daily commute is only 8.5 miles each way (about 30min) which is not good for mpg--the ICE gets fully warmed up and is most efficient just about the time I arrive at work and shut off the car.
My MPG average tends to shoot way up when I take longer trips, even on the freeway.
Still, I could get 50mpg with short trips but I would have to work at it MUCH harder...via slow steady acceleration, pulse and glide, coasting down to stops, etc. I think if you keep working at it and experimenting you will get there.
Try perusing the posts in this forum 'cause there are lots of tips and theories on how to maximize your MGP. Good luck!

[Tideland Prius]

hmm... thanks for putting the location in your profile, it makes answering the question a lot easier.

It seems odd since isn't Eastern WA more or less flat? Or do you live in the hilly parts near the passes? You seem to be doing well and no doubt you'll be able to improve. Turning off A/C should make a difference since the A/C isn't draining the battery, leaving you more juice for powering the car if needed. Also, if the A/C is running at full blast to keep the temps down (should be in 90s this week), then your mileage will take a hit. Try bumping the A/C up as high as you can stand without overheating or feeling uncomfortable. Also, make sure you're not taking short trips. Short trips will erode the nice mileage quite quickly. By short, I'd say a 5 min drive? or a quick sprint up a hill then stopping.

Headlights won't make a difference.. or at least not a big enough difference to notice.

For the battery, nothing. It's colour-coded so it's easier to read. green is much easier to see than counting 7 bars. 7 and 8 bars are green, 3-6 are blue, 1-2 are pink (or purple, depending who you ask).

Keep up the techniques you're using. I don't see any problems with that. You might crack the 50mpg in late Aug or early Sept before the cold temps set in and the switch to winter fuel.

[efusco]

http://priuschat.com/index.php?autocom=art...howarticle&id=3

[galaxee]

Evan's link above is possibly the best advice available for anyone concerned about their MPG. check it out and see how you do

and pff, how can i forget, WELCOME to the fourm! feel free to stick around, check out the features of the site (Danny has set up a fantastic set of resources here)- check out the "features" menu on the top right of the page and browse around a bit.

[Hutchings]

Yes, here in the Tri-Cities, we are very flat. Dry and dusty too! 95% of our trips are less then 15 minute outings. I will keep following the sugestions offered and appreciate all of the replies. Sure love this Prius. Too bad it still fits over 250 bucks worth of groceries from Costco in it. I kind of hoped that my wife expensive weekends at Costco were over, but nooooo, darn thing has too much cargo room!

[tomdeimos]

I'd suggest you check your car by forgetting tank mpg and trip mpg. Look at your steady state mpg at a fixed speed on level road over a few minutes after the car is fully warm and you are in stage 4.

Note the temperature and humidity too. Then plug into Wayne Brown's palm program if possible, or else look up some of the tables of mpg vs speed that have been listed here based on this simulator.

If you do this when there is minimal wind, you should get a good idea how you are doing.
Note that you may need over 12,000 miles on your car to get as good mpg as others here report.

After doing this, try a loop of about 30 miles or more on back roads where you can drive steady at speeds of 35 to 40 mph. Do not pulse and glide. Just drive steady. Find a route where you have minimal stops.
With AC off, you should be able to exceed 70 mpg. Reset your mpg when starting. It is far more useful on trips than measuring tankfuls which you can calculate anyway. After you do this and see great mpg hopefully over 70 mpg you can then work on things like pulse and glide to try to do better. Till you get the basics right trying the fancy stuff might just make things worse for you.

Now if you can get good mpg, just somewhere, you can then learn to see why it is bad in your normal driving. Could be trip lenghts, not getting into stage 4, AC use, really big mountains, too many stop signs or bad traffic, etc.

When you can be comfortable turn off the ac and open windows. Every time I've tested, mpg has been better with AC off in temps up to 85 degrees. If you drive 80 mph maybe AC is better than opening windows but then you won't get great mpg anyways.

Finally remember brakes are for emergencies. If you use them to stop fast or to stop every mile or two your good mpg will be gone.

[Jeannie]

<div class='quotetop'>QUOTE(galaxee @ Jun 26 2006, 07:29 PM) [snapback]277052[/snapback]</div>

Evan's link above is possibly the best advice available for anyone concerned about their MPG. check it out and see how you do
[/b]

Ditto
I had the same concern on my first tank and posted much the same question. That link explains a LOT!

I drive short trips - 5 miles each way to/from work. I'm half-way through my 4th tank of gas; first tank averaged 43 while I "learned" to coast as much as possible to slow down, anticpate the lights on my daily route, etc. It was easy to learn by just glancing at the 'consumption" screen and noticing the 'instantaneous' reading - example - there's a half mile stretch of road between two stop lights, and the second light says 'no turn on red'. It's a 'back way' with a 30 MPH speed limit. Often there's no one near me on that stretch of road. If I keep my foot on the accelerator to maintain a speed of 30, I ALWAYS have to stop for that red light. If, on the other hand, there's no one behind me, I'll 'coast' and perhaps tap the aceelerator when I slow down to 25, unless I'm very close to that stop light - I've let it drop down to 15 mph and still have to stop at that light. I then turn right and go through a small town for maybe 1.5 miles, where the speed limit's 25 or 30 - I rarely try to push myself up to 30, because shortly after the change in speed limit from 25 to 30, the road dips down for a bit - the car will get up to 30 without my stepping on the accelerator.

So my next couple of tanks were about 48 mpg, and the fourth tank looks like it's heading the same way, and I'm not likely to see much of an improvement until I happen to take one or more 'long' trips on a tank of gas, where 'long' means driving for 45-60 minutes instead of the typical 15 to 20 I drive on my commutes and the even shorter times for my 'errands'.

Several people have said they see an increase in MPG around 3000-5000miles, and some say that's because the tires are now 'broken in'.

Good luck with your mileage. I'm thrilled to be getting at least twice the MPG as my old car! So this is my wisdom after 10 weeks of ownership <g>

[haceaton]

<div class='quotetop'>QUOTE(tomdeimos @ Jun 26 2006, 07:41 PM) [snapback]277058[/snapback]</div>

I'd suggest you check your car by forgetting tank mpg and trip mpg. Look at your steady state mpg at a fixed speed on level road over a few minutes after the car is fully warm and you are in stage 4.

Note the temperature and humidity too. Then plug into Wayne Brown's palm program if possible, or else look up some of the tables of mpg vs speed that have been listed here based on this simulator.
[/b]

This is a great suggestion. I've only put about 500 miles on my new '06 and have averaged a sad 40.2 MPG so far. I also have an '02 Prius and I've driven it since Oct 2001 and have a lifetime average of 44 MPG on that vehicle. So I'm not a newbie to driving the Prius for good mileage. This time of year my '02 gets about 48 MPG with the same kind of driving I've been doing in the '06. Theoretically the '06 should get better mileage than my '02 but so far I wonder if there is something not quite right with the car. It's definitely not the A/C, since I sweated it out for about 100 miles without using A/C and saw only a miniscule improvement.

Like the topic starter of this post, I notice my '06 starting the engine when it really seems like it shouldn't. For example, going down a hill with the foot completely off the accelerator pedal at a speed of 36 MPH, and the engine starts! The battery icon shows 4 bars and the A/C is off, so I can see no reason to start the engine when it was just running on the way up the hill and shut off when I first took my foot off the gas.

One other thing I notice is that the starting and stopping of the engine is far more noticeable in the '06 than in my '02. I can feel a small but distinct "bump" in the car acceleration most of the time when the engine starts or stops. My '02 is much smoother in this regard, it's relatively rare that I feel its engine start/stop.

[jkash]

<div class='quotetop'>QUOTE(Hutchings @ Jun 26 2006, 04:40 PM) [snapback]277057[/snapback]</div>

Yes, here in the Tri-Cities, we are very flat. Dry and dusty too! 95% of our trips are less then 15 minute outings. I will keep following the sugestions offered and appreciate all of the replies. Sure love this Prius. Too bad it still fits over 250 bucks worth of groceries from Costco in it. I kind of hoped that my wife expensive weekends at Costco were over, but nooooo, darn thing has too much cargo room!
[/b]

Your short outings are your biggest problem not achieving higher mpg. You need to drive at least 30 minutes to make up for the first five minutes being low due to warming up. I have to admit that I try to have my wife drive her car if we are going to do a short trip. She thinks I am a bit of obsessed, but she's getting over it.