A surprise on this last tank

I took at 120mile trip and the CONS reading was 59.7 at the highest point, using the cruise control mostly. I was anxious to fill up the tank and see how that indicated mpg would help the overall mpg. Surprisingly it was only 49.1 when I filled it I thought sure that 120 mile run would have sent me to at least 55mpg again or maybe better.

I suppose all the fuel I saved on the trip was gobbled up by my short hops to the grocery store only about 1 mile away and downhill at that. Yes I can glide down to it but of course returning home it's all uphill and I have to get into the power area of the ECO mode to get up the hill <sigh>. There is no other way to get back up without going uphill somewhere.

I've really been paying attention to that 'sweet spot" on the HSI display between no re-gen and no EV. It's not too hard to find and maintain once you get the hang of it. I only wish that the HSI display of the outline of the car would show me where that spot is, it might make it easier to see. I realize I'd be looking to see nothing but EV power alone but to keep it there with that display for me isn't easy.

Still learning and having fun with it too!

This forum is such a great source of info with tons of REALLY informed and knowledgeable folks I love it!

Going uphill isn't too bad on the fuel efficiency if you can design your route there is a flat or downhill section of road before the uphill climb where you can add about 10 mph to 15 mph before the foot of the uphill climb. If you can add a few more mph to the Prius that extra momentum can help take the strain off the gas engine during the climb and lower the overall fuel cost. This technique is called driving with load (DWL) within hypermiling circles.

If you want to get the really good highway fuel efficiency on the Prius you need to keep the Prius speed under 60 mph-- with 50 mph to 55 mph the preferred cruise control setting.

If you combine several short trips together with less than 10 minutes between each trip - the Prius will get better fuel efficiency with each successive trip that you've strung together.

The most efficient way to get the most speed out each ounce of gas the Prius burns is to synchronize the accelerations with a downhill grade. The sweet spot for the ICE on the HSI jumps around a bit but for SuperHighway Mode (SHM, low rpm =992 to 1100, gph=.50 to .70 ) its basically under the "ECO" capsule - yeah smack in the center. You really need a ScangaugeII or something like it to even have a chance at keeping the Prius in SHM - it's really difficult...

HTH

Walter Lee
aka "HyperDrive 1" on cleanmpg.com
2010 Toyota Prius III, Blue Ribbon/Dark Grey, OE floormats
Yokohama Avid S33D (front 48 psi , rear 46 psi )
2 ScangaugeII ( AVG, MPG/FwT, SoC, Flv)( TPS, IGN, GPH, RPM)
no grill blocking
Odometer =25000 miles
overall mpg 60 mpg (calculated)
avg speed 17 mph
Last tank 710 miles/10.42 gallons of E10, 68 mpg, avg mph=17

For the record, driving with load is illegal because it always requires breaking the speed limits.

With that being said "in my imaginary prius on imaginary roads" DWL is one of my best techniques to conquer all the hills around here and at the end of trips I used to lose 0.5 mpg per trip, I can now at least break even and end up at the CONS that I started with, even after losses from engine warm up.

I hate hills that require PWR to climb over 16 mph. On the flip side, I lug the car up hills at 16mph if nobody is behind me at night leaving work. It's all uphill to start, so I go just shy of maxing the ECO bar out and I usually lose 0.3 mpg on 1/2 mile hill climbs. in PWR bar I lose 0.5 - 0.6 on the same hill so if nobody is behind you, do some experimenting to find out how much throttle you need to climb that hill at the lowest possible speed without being a danger, without annoying yourself, and cutting as much mpg loss as possible.

Also, when you grocery shop, make it 1 big trip, or run other errands while you are out, avoiding short trips, or multiple runs to the same store in a week will save gas and $ for you also.

DWL does not *always* require breaking speed limits. I use it often on 70 mph roads: I speed up to 75ish before the hill and crest at about 60 mph. On flats I drive about 65 mph.

The meter has a strict line between ECO and POWER, but it is artificial. Nothing particularly horrendous happens to fuel economy if you dance over the line.

? What part of "speed limit" don't you understand?

OK, make that 70 mph at the start of the hill, 60 mph at the crest so that you can stop whining.

*sings*

Breakin' the law, breakin' the law......

*rocks out Bevis and Butthead style*

YOU DON'T KNOW WHAT IT'S LIIIIIIIIIIIIIKE!!!

He heee heeh heee that sucks man.

I really don't get the love for Judas Priest. And not to get Butthead wrong, since he loves Judas Priest and all, but that video was horrible.

Anyway, to the OP:
- if you did a short fill in your excitement after that trip you can't rely on the number. The shorter the fill, the bigger the margin of error.
- I absolutely agree on the sweet spot, it's really not obvious. However, reports are that a small amount of EV doesn't make much difference so just make absolutely sure that you avoid regen.
- Short trips do indeed suck, especially when you're immediately going uphill.

I was always more of an Iron Maiden fan but this song was fitting. LOL

A little harsh perhaps... And this is coming from someone that try's to drive the speed limit when possible. Personal safety from those that road rage is a normal way of life sometimes mean doing for me 5mph over the limit for me.

As for SageBrush, I also follow the DWL method of about 5mph over the posted to help in the hills. Though sometimes I say damn it all and do what I think is safe after first hand experience. There is a hill on my commute that deer seem to love on either side of the crest (go figure <eek>), so I will never crest that hill at more than 25mph on a 35mph posted. My safety and damage to my car outweighs the blowhard behind me.

To the OP, missing some data here - but your short trips may have played a big part in the 49.1mpg you got (BTW, still respectable). The missing part if I read your post correctly is what the CONS showed at the actual time of fill-up.

The issue I think in folks not happy with their mpg's, folks like F8L and even more xtreem folks that get way above the average. But looking at Fuelly for the Gen III's between 47 and 49 mpg's seem to be the norm. And it was those numbers that made me give up my Baja.

Took me a bit to learn how to drive the Prius to get the best mpg's for the way I drive. Add to that because for some of us, this is the first time we have had a car that gave us mpg read outs as we drive. In the end the Prius becomes like a video game because of that.

And if you look at Fuelly on the 2010-2012MY's there is a marked difference in average mpg's. For 2012's the difference can be explained by lack of winter driving data. For some of us with 2012's we bought when gas was above $4 a gallon and facing $5 a gallon. The Prius got us thinking about our driving habits more.

ChipL is right on.

Some of us do go to rather extreme lengths to get 20%+ higher than EPA numbers. There are also a lot of people who drive in terrible conditions AND frankly drive like crap so their fuel economy suffers. I like when those people have Fuelly accounts because they balance out people like WalterLee and myself. My first 20 tanks or so during my testing phase averaged only 50-52mpg and that was with only a little winter driving. By the end of next winter I expect my average mpg on Fuelly to drop into the mid 50s unless I continue to try really hard.

Thanks Justin...

Took me a couple of months of driving the Prius to get the hang on getting the best mpg's for my style of driving. I am sure that I could be getting high mpg's if I were a true hypermiler. But in this area that can be a problem, and even though I like the slower pace in driving my regular routes - I am not wanting any more road rage than I see day to day. Never mind I know where the ops hang out for ticketing - with the added value of "enforcement zones" with tickets starting at $250 regardless of how much you are over the limit.

Just wish I could get some $ from those that have tailgated me, flashing their headlights and such - only to have saved me and them from an expensive ticket.

I wish we could have a requirement on PriusChat that one has a Fuelly account BEFORE commenting on mpg's. That would be a good start, the other is like the both of us that provide details on how we got to the point we have. Some of it was testing in varrious techniques and and configurations. Like my test of using the Thule Platform rack on our beach run. Next week I might get the chance on my birthday to do a day trip with the fiancé and see what I get without the rack....

Hi ChipL.
In the very first line of my post I mentioned that he CONS was showing 59.7. I didn't go and fill the tank up straightaway, I waited until it was blinking and then I filled it up expecting to see a higher number for that tankful.

That's when I opined that my daily short commutes etc. probably gobbled up all the fuel I had saved on the 120 mile run with the CONS showing 59.7.

Realizing that everyone's location may not be conducive to getting great mileage is a great help, and I put myself in that category. I am still way ahead of the game with the 49 mpg anyway. When you add to that the fact that I like to drive the car regardless of the mileage it's still pretty cool!

I'm assuming not, but do you remember what the displayed MPG was when you filled it up? I misunderstood your first post as well (that you filled it up with the displayed MPG = 59.7, but you actually saw 49 mpg).

I had to explain this to some of the TDi folks as well. You cannot simply compare mpg between cars, even if they are identical models. Commutes, conditions and driving styles can have a profound effect on average mpg! 49mpg is pretty damned good. Even the majority of the TDi folks that drive mostly freeway barely get that.

Hi Codyroo,

Now I;m not understanding you lol!

Maybe I am not understanding your terminology when you say " the displayed mpg when you filled up?"

The only mpg that I was referring to was the CONSumption which showed me the 59.7 mpg number. If I shouldn't be even looking at that as a loose mpg indicator then the error is mine. I filled the tank and computed the actual mileage, which was 49 +/-. If there is another readout I am missing then forgive me, I don't have a Scangauge to go by. But hey Christmas isn't that far off....

Regards

I think the problem here is we need to be clear about what you read on the display AT THE TIME of fillup. Not what it was at some point prior to driving another few hundred miles on that same tank.

So what was the display reading when you actually filled up?