Factors affecting MPG

I am driving my 2nd Prius. The first was a 2002, currently driving a 2005. Overall fuel mileage with the 02 was 49.5 determined by averaging fillups and topping off using a hand held calculator. Mileage would vary from 3 -4 miles +/- to on board system. In our 2005 model with 41,600 miles, our average is 51 MPG overall. When gas we were using went to 10% ethanol, our fuel dropped from 54 MPG. Driving is mostly at 55 MPH or less (about 50%). A trip to AZ from FL yielded 48 MPG and speeds of 75 MPH out west. Northern AZ in mountainous terrain caused a decrease to 44 MPG, lowest ever except for 60MPH headwinds in South Dakota in 2005 on I-70. Our mileage at that plumetted to 36 MPG.

Am now replacing tires. Looking at Bridgestone Plotenza 960 SAS to replace Goodyear OE Integrity which were rough riding.

I use the "B" shift position when in city driving around Orlando, FL to ease use of brakes. Have not noticed any increase in fuel consumption.

Have noticed in both cars that when they sit without running for 7 - 14 days, that fuel consumption goes way up until main battery is back to 65% and then tapers off to normal MPG. Do not judge fuel consumption under these circumstances.

 

When I listed "Aces Rules" earlier in this thread, I forgot to mention grill blocking. From what I've read here, it really helps in the winter months. I haven't tried myself. I suspect that if I were to do it, I'd want a Scangauge II to ensure I'm not over-blocking for the driving conditions? Last winter I was still figuring things out. So I may want to explore this avenue before Spring.

As for the long hills issue. The problem is battery capacity. There is one road that I travel on occasionally, that looses 300' of elevation in 1.5 miles. Ideally, if you had an EV button mod, and realized it ahead of time, you'd go to EV mode and drain down the battery by the top of the hill. But with the stock Prius battery, even then I think you'd max out the battery on a hill of even this size. And of course the fact that you go down then back up hills, while storing and using electricity, will give you significant losses over a flat road of the same length.

On some moderate hills in my area, I can accelerate to 42 mph, then back off enough to turn off the ICE. It's not nearly as good as Pulse & Glide. But at least it does cut some of the engine run times.

I also didn't talk about types of tires. I am using the stock Integrity tires. And from what I've read, there are many who dislike these from a ride comfort or traction/safety issues. But some of the replacing tires cause a loss of FE. I don't recall anyone posting about tire brands that improve FE over the Integrity's. So that's why I didn't mention it.

 

Yea, I have found that a EBH combined with Grill Blocking helps a lot - especially short trips which I have every day. Also, I have my tires pumped up pretty good - 60/58.

I have a related question about something that came up earlier in this thread. I had always assumed that the Prius generates electricty when you apply the brakes but someone earlier suggested no - that it is coasting that regenerates. Does anyone know how this regenerative braking works? Do you have to apply the brakes or does it work when you are dragging along with your foot off the go pedal? Does applying the brake pedal have anyting to do with regeneration? Despite all my reading I still am not clear on this.

 

rpg51,

You get regenerative braking, "regen," both when you're in a "blue arrow
glide" and when you're braking. You get just a little recovery in the glide, and
a whole lotta recovery when braking -- down to 8 MPH when regen cuts out
and its then all mechanical braking down to the stop.

IIRC, the regen in the blue arrows glide is a programed-in very slight braking
action. It's meant to simulate the internal friction experienced with an
automatic transmission. Apparently, it was thought that most folks would panic
if the car just kept rolling and rolling along. Thank you Mother Toyota.

 

Rokeby,

It's not a glide if you have regen. Not sure what "blue arrows glide" would be as the arrows are green/turquoise.

 

I think he is talking about the situation where you remove your foot from the go pedal and arrows appear from the wheels to the battery.

 

Shawn Clark,

I think of "regen" as a diminshing glide with the benefit of a small amount of
energy recovery. (I practice Driving Without Brakes, DWB, fervently and
don't see that many big hills, and drive mostly on urbal streets, so "regen" just
happens on occasion and is not a major element of my energy management
except in special cases like when exiting a freeway.)

Well, as to color I remember the "regen" arrows as being blue on my MFD.
I suppose that color, like beauty, is in the eye of the beholder. But whether
we call it blue, or turquoise, or green, -- or teal for that matter --it is easily
distinguishable from yellow.

 

Rokeby,

The problem is that you are usingterminology that conflicts with that normally used and that will only confuse readers. It isn't a glide when you lift all the way out and it is regenning, so don't call it that. It is more analogous to "coasting" as the previous poster described it, because the mild regen simulates the engine braking effect that occurs in non-hybrid vehicles. Glide is the term used specifically to distinguish the no drive energy transfer state (no arrows.) Letting the car regen is not gliding.

 

Back in July '08, information was published here that showed conclusively
that when a Prius in the "no arrows" state as shown on the MFD, energy
was flowing out of the HV battery, to MG1 which was acting as a motor,
and powering the front wheels at about 0.7 HP. The energy flow is
approximately three times needed to keep the CPU(s), ECUs, and other
miscellaneous elec. equip. running. What up to that time had been
thought to be a zero energy flow state true glide isn't, and apparently
never was.

Further it was found that when a Prius is moving forward, the closest
thing to a true glide is to be in Neutral where the energy going out of
the HV battery is close to what would be expected to keep the
CPU(s), ECUs, etc. running.

I don't know what to make of it, but the term "no arrows glide" has
continued in use as if were correct. With this new information, the best
we can say is the no arrows "glide" isn't a true glide at all. It might be
truthfully called an augmented "glide."

You can "Read All About It!" here:

http://priuschat.com/forums/prius-t...parison-methods-pedal-control-vs-neutral.html

 

I'm getting a headache!

Sometimes I wonder if we are all taking this MPG thing and the Prius driving techniques a little too far.

Right now I'm told we are going to get our first snow tonight so I have to go home and swap my Integritys for my Nokian R snow tires. It will be interesting to see how this engineering marvel works driving in the mountains in a snow storm. Say a prayer for me!

 

rpg51,

Hurry-up quick read post #4 in this thread about how to use, and what to
expect from the Traction Control system:

http://priuschat.com/forums/prius-technical-discussion/42846-traction-control-worked-i-think.html

 

This is why I go to N when I'm in the glide portion of P&G. During the daytime without headlights, the Scanguage reads a current draw of 1.0-1.1 amps coming out of the HV battery. At about 32 mph though, that starts to go toward 0 and will actually go to a small amount of regen around 35 mph. I have seen as high as 17 amps of regen while in a no arrows, neutral, ICE-off glide. When you reach 37 mph, the regen goes away and the current draw drops back to the standard 1 amp of draw from the HV.

 

Yea, I've read all this stuff and - well - I don't want to pre-judge so I'll hold my fire until I have some experience with the thing in the snow and ice. I'm real skeptical though. I had a bad experience on two steep gravel driveways. I think a lot, not all, that you read is written by people who have driven in the snow but in fairly flat terrain. So, like I said, I'll hold my fire for now.

I got home and had a scotch and now I'm in the couch watching Chris Matthews thinking about another one, (scotch). Maybe I'll just take the Tundra tomorrow. Its cold and damp out there in the garage right now.

 

This is my first post... Love the prius; 4 years and 85,000 miles, and priuschat; a few days so far. Things that affect MPG… My hitch allows me to hook up toys and threaten my warranty.

I refer to my prius+trailer combo as my “35mpg pickup.” I decided to be the Guinea pig for the prius community and test my prius with all kinds of trailers of various sizes. My first trailer test was to creep very gingerly, moving my horse trailer within my field. It worked and nothing broke, yes. If anyone is interested, I have 1 year experience towing max loads at max distances, MPG stats, 35,000 miles, and no related problems yet. I always worried my 100,000 mile warranty would be in jeopardy, but at 109,000 and no warranty left or used, I love my Prius for its endurance, longevity, and resale retention.

At 85,000 miles, I had one problem: Enhanced VSC, (!), check engine (all amber), (and /?\ (Red), I think the VSC and (!) lights went off with restart. Anyway the Toyota service couldn't find any codes and reset the lights. At 107,000 the lights returned on I84 to Boise. Restarts made the two lights go out but driving made them come on again. Called Boise Toyota, they said not to worry unless driving on wet roads, etc. I Continued to Portland with mostly lights coming on, and resetting at convenient stops. Started reading posts and things VSC (Hobbit, Bob, etc) and found design problem under engine. On to Lewiston Idaho and returned to Utah continuing to fight the lights. I can’t find that post about the ill designed engine plate rubbing and damaging the computer data cable, but moved mine a little and took pictures, now the VSC light hasn’t returned in 130 miles of driving 2 days now.

Enough said, I welcome comments and help and all.

 

Just remembered. I agree not to use the "B" mode. After about 70,000 miles use(37k to 107k, it hasn't been detrimental to the transmission, but I recently read about how the brake pedal regenerates power before applying brakes. This convinced me to give up the "B" mode :car: and use the brake pedal which I think has helped my MPG. I still have original brake pads at 109,000 miles:cheer2:

 

Sorry but you can only go so far in all electric mode, even if you are only going slow. The batteries just dont hold that much usable charge (they're 200 Volt 6.5 amp-hour but I think that less than half that amp-hour capacity is actually used so as to maintain long service life). Even driving slow on flat terrain I think you'd only go a few km at most in all electric mode.

BTW. Does anyone have any more exact figures or reaseach on this?

 

What tires get best gas mileage???

 

What tires get the best gas mileage... I am in need of tires now.. thanks