Slightly dissatisfied with my Mpg

Between 44 and 52 depending on driving and terrain. (I live on a mountain and have a couple thousand foot vertical drop between the main city and my house). Determined by looking at the MFD. You cannot count on "at-the-pump" calculations because that assumes the tank is the same size each time. Our cars have flexible bladders and it varies by ALOT! So the MFD is your best bet other than averaging over many many fills.

That is a big cause of MPG loss. Go to Petsmart, get aquarium tubing. $1.99 for 8ft of clear tubing and it fits like a glove. I just did this today actually. I still need to do more since it takes a couple hours at this rate. Alternatively you could buy a true oil siphon or drain it and refill properly.

My newsed car's alignment was off (slightly, but still off).

The covers wont effect mileage noticeably at all.

BINGO... This is just flat out the wrong way to drive a Prius. It is very counterintuitive, but you should accelerate aggressively (not to the floor, but with oomph) which is called "pulsing" and then you want to take your foot off the accelerator completely and then press down just a little bit (like with your big toe only or something) so that there are no arrows at all on the MFD energy screen which is called gliding. So Pulse to speed limit + 5, glide back down to speed limit or a bit below, then pulse back up, and glide back down. You should try to never use regen when just driving down the road. Meaning dont accelerate and then take your foot off completely then accelerate again. That's just wasted energy. Using electric only is a very poor idea as well. It almost always hurts your MPG. One difference is with the EV mode accelerating briskly in electric up to something in the teens and then using the engine to keep accelerating. This can help the fuel economy in certain situations.

Just turn it off and use the windows unless you go over 55mph or so.

I used premium for the first couple thousand as it always gave me really good FE in my Honda Civic, Lexus RX, and Toyota Rav4. However the Prius for some reason likes 85 quite a bit and it does help. So cheaper gas actually makes the Prius happy.

So basically, you can drive the Prius like any other car and get 40's which is still far better than anything else on the road. Or you can drive with a little adjustment and get much much better. If you are really interested in fuel economy, then you can become a hypermiller elite!

And :welcome:

 

Thanks for answering my questions! It's refreshing to see that vs. random low post count folks people griping about their mileage, providing scant or no details (leaving us guessing), sometimes to never return...

Your mileage does sound a little a bit low for the speeds and trip lengths you're describing.

Agreed w/2k1 about NOT trying to accelerate so slowly that you're in electric only and on draining out the excess oil.

As mentioned in the 1st PDF at http://priuschat.com/forums/gen-ii-...angauge-best-threads-mileage-improvement.html

Hopefully someone can chime in about those tires as I don't know how badly (if all) those tires hurt mileage vs. the stock ones. I don't recall seeing anyone here on PC installing those.

As for turning off AC... uhh, even though I used to live in California, I don't think I'd be able to tolerate 93 F w/no AC for long on an AC equipped car. But yes, using it will hurt your mileage a bit.

 

I only use regular fuel.

 

I would echo what Cwerdna and and 2k1 said, although I would disagree about A/C usage (good god, 93F and Humidity! Use your A/C, there will be a MPG hit, but there is a MPG hit for all cars using their A/C).

 

Another reason for the A/C besides creature comfort, that has been mentioned in other posts, is to keep the HV batteries cool.

 

Great work on posting all the info Jamebarron, it makes it so much easier for people here to quickly find your trouble spots.

I can see at least 5 things that are bringing your MPG down there.

1. Oversize tires. Though I assume that you have the "touring edition" prius with uses these as standard so perhaps not much you can do about that.
Deduct 2MPG.

2. Not using LRR (low rolling resistance) tires.
Deduct a further 3 to 6 MPG.

3. Driving habit. Trying to accelerate on battery only is an inefficient use of the battery power.
Deduct another 2 to 4 MPG.

4. Lots of A/C use.
Deduct 2MPG.

5. Overfilled oil. Personally I've never noticed much of a hit on MPG when I've had mine overfilled by a smaller amount (about 1/8") but various others here swear they measured a 1 or 2 MPG hit there. I'll ignore a 1/8" overfill (some here wont) but I wouldn't be comfortable going 3/8" over. Make sure you're using a really good quality 5W30 oil and don’t overfill. Deduct 1 or 2 MPG.

OK let me add straight away that I'm just reporting what I see as the factors that would make you fare worse than the guys getting 55MPH, I'm not saying that you necessarily can or should "fix" every issue. Take the A/C use for example, I'm not telling you not to use it, you need it. I'm just pointing out the factors.

Adding the median of the above 5 issues (all just wild guestimates of course) buys you about another 13 MPG. Adding this would bring you up to about 53 or 54 MPG right.

 

Hi Jamebarron. Here's a bit of extra info re my last post.

I searched for the rolling resistance of your tires but I couldn't find much. I found this on a Honda Civic hybid MPG forum. Interesting read.

Re driving style. I wrote this a few days ago for another thread. Let me just copy and paste it here.

 

The touring has bigger rims so it takes different tires. I don't own a touring edition so I don't know for sure whats best in that size, but if you ask around here I'm sure you'll get some suggestions for a LRR replacement.

 

Yep, touring's got bigger tires. When I asked for tire recommendation for my non-touring at http://priuschat.com/forums/gen-ii-...-another-help-me-decide-tire-thread-06-a.html, I got a couple recommendations and was also sent to another thread.

 

I'm not sure I would agree with this amount. I've set my A/C to auto, usually above 76F on the MFD (and the hotter it gets, the higher I go. 90F external usually has me at 81F internal on the MFD). I've not seen a hit using this method. Heat, however, is a much bigger drag on MPG for me.

Caveat >> I drive below the posted limits, live in a fairly flat state, drive mostly highway milage, and have a very long commute. However, even when my wife drives the car (and the Scanguage captures much higher speed runs for her than it does me ), it's very rare that even she doesn't return in the low 50's for a trip average over several hundred miles using the same A/C settings.

 

Watch the Energy display. You want to use the battery as *little* as possible because charging and discharging a battery is inherently inefficient. That is why pulse-and-glide is the best strategy.

 

Accelerate briskly from a stop, then ease off.

Watch ahead, and when you see the traffic lights going against you, ease off sooner than you are used to. Anticipate traffic patterns, and already be coasting slower when you have to stop. If a stop light will be changing momentarily, see if you can avoid coming to a dead stop (slowly coast to it)... starting up from a dead stop takes just a bit more power than speeding back up from a crawl.

Using cruise control in hilly areas doesn't work well. You want to ease off the gas just as you come to the crest of the hill, and let that inertia work for you - on the way down, and then again on the way up the next rise. Unless traffic is intolerant, let the speed vary a bit as you go up and down the hills.

 

Interesting.

Are there numbers to back this up?

Years ago, when a friend's wife bought an '04, and we were all interested, I read something online, (probably by Hobbit) concerning drag coefficients that pretty strongly implied that above 22 to 25 mph (apparent wind) the additional drag would overcome the loss from running the air control. Assuming of course, folks
are being reasonable with the A/C.

I can 'feel' the windows at about 40mph, regardless of how I have them open.
crack this one, and the diagonal one, and so on. In some cases, the 'thumping' I get from the air pressure of having the windows open in some configuration or another gets severe enough to make me think a window is going to pop out.

the drag at 55 is crazy. Feels like carrying a parachute or something.

 

I have no idea. It is second hand info, and I believe there is some truth to it. Obviously every car will be different depending on its shape and AC efficiency as well as how hard you are running the AC. But the two versions I have heard many times over for many years are "above 55" and "at highway speeds" which from the Eisenhower days were 55 I believe. So the cutoff is probably around there +/- some margin.

I never really paid attention ayways as I prefer to have my windows cracked at 80mph than the AC. I like the noise of the road/traffic/wind to keep the drive interesting.

 

Mythbusters tested this 2x, but they didn't use Priuses (so obviously, no cars w/electric AC compressors).
MythBusters (2004 season) - Wikipedia, the free encyclopedia (1st time)
MythBusters (2005 season) - Wikipedia, the free encyclopedia (retest)