4th generation coming 2015!

Judging from a press release from Toyota, it sounds like Toyota will indeed have more than a couple surprises to show in the next year...Efficient SUV? Efficient 8 seater? Looking forward to it. I think Toyota will reach 55MPG+, perhaps even 60MPG

Edit:

Here's the article in question Toyota ponders awd for next-gen Prius

 

We've been saying this all along how LiIon would revolutionize mpg combined with prius superior synergistic technology but they can't give us a tiny one.

What good is a battery for regen if it's full all the time with no place to put the regen ?
At the same time, with that headroom held in reserve there still has to be plenty left for actual distance and performance... This means the need for a respectable sized battery.
You would then get phenomenal mpg without having to change the whole technology.

At this time... The battery is the bottleneck.

Toyota has this gigantic NiMh factory they want to utilize why the competition is catching up!

And diesel is not desirable it it's gonna cost 25 percent more for every drop of fuel you put in it versus gas. Plus they are somewhat obnoxious with their clunky noise!

 

The HSD already has infinite gearing implemented through e-CVT.

I imagine the rear powered axle will be engineered for small size, low cost, low weight, and high torque for brief periods.

 

No use, but 'full all the time' is rather unlikely. You would have to live in a perpetually downhill area

Engineering is a game of trade-offs. Under-utilized resources cost money, weight and space.

 

Granted but currently we have a battery with a total capacity to get you a couple miles down the road if your lucky.

So there's little play or opportunity to utilize but a portion of power saved from regen.

On long trips at high rpms of efficiency Atkinson engine, it's no big deal to slowly slice off juice to the battery for later use.... But no good if no reserve.

The existing battery is really only good to reuse brake and coasting regen, that's about all it can hold since everytime you brake or coast, bits assumed your getting ready to re-accelerate again.

 

Sounds about right to me too, at least for the upcoming release. Toyota Engineers are on record saying that they are working in the 'diminishing returns' area of the curve these days but their internal goals remain an improvement of 10% in fuel economy each revision.

Since I live in snow country, I find the thought of a 55 mpg, adequate_ AWD car *very* appealing.

 

I am not following your reasoning.

How about if we ask a practical question:

1. How much will fuel economy improve for 90% of drivers with a 50% larger battery ?

My distinct impression is very little. As a matter of fact I think Toyota only put in a battery as big as we have to mitigate the loss of capacity as the battery ages. As that aspect of battery chemistry improves I expect *smaller* capacity batteries in straight hybrids.

 

The prius ICE is not efficient at LOWER speeds, do it's performance is dependent upon accrued energy stored in the battery giving it the "edge" till rpms climb. Then the Atkinson engine is extremely efficient, do much so that a tad extra work to make energy while it's very efficient pays off when going slow and not efficient.

The starting and sudden accelerations are an easy task for electric torque, not so much for the engine.

It would be doing what it's doing now, just to a much greater degree.

But historically LiIon batteries were spendy and Toyotas nimh were very cheap (profit margin) since they own the factory, but good amp/hr capacity in nimh is not practical due to size and weight, nor does it allow as great a use of total capacity without killing it prematurely.

Tesla is stealing the show on this one. Using the Atkinson when already under heavy load would do wonders IMO for total mpg.

This LiIon greater capacity is one reason the plug-ins get better milage even without plugging in, but the battery is still not big enough.. It could go much larger.

 

Not at lower speeds put at lower power, true lower power is used under low speed but not necessarily.

There could be a benefit with li-ion if this means higher charge discharge efficiency, capacity is not the reason why PiP gets better mileage. But what is the difference? EPA measured the same 50 MPG with PiP.

 

An SFC map shows the details. The efficiency map is a function of torque and RPM. The Prius ICE does a splendid job of handling most low power situations from about 10 kW.

The better question for Windstring though is how often is the battery so depleted that the ICE must handle low power situations all by itself, and what is the eventual hit to average fuel economy. My experience driving Prius for about 10 years is rarely and negligible. Moreover, in the case of a depleted battery the ICE is going to run at a high(er) power rating to move the car AND replenish the battery, so this is probably a mute point entirely.

A big(ger) battery is just not going to improve fuel economy a worthwhile amount for enough drivers. More than most, I see the limitations of a small capacity battery because my car goes up and down a couple thousand feet of elevation within 5 miles. While my Gen2 would often deplete the battery on the uphill and then the ICE would labor to the top, this has been fixed by the larger ICE in the Gen3 series. I do see a full battery on long descents but that is way less than 5% of my total miles. I'm sorry, but this is a solution (bigger battery) looking for a problem.

I've no doubt we will get big batteries for plug-ins. Not for straight hybrids.

 

Not trying to argue, but before pip came out they made kits that increase your battery capacity considerably and that alone increased total mpg notably.

Think about how many times you come to a stop or brake and look at your battery meter to see its already full? (almost always)

 

I have 3 prius, and 1 Avalon Hybrid. two are Gen 2 with 220k and 240k, the Gen 3 has 160k., Avalon has about 28k all already

I'm not taking about folks who are retired and barely get the car warmed before they stop, I'm talking about using it for work, pleasure and travel.

Any power used at low speeds come from one of two sources 1. Battery (derived from gas regen) , AND 2. ICE which is not efficient at low speeds.

The electric is not free, it came from gas. The electric portion is efficient at low speeds but the benefits of the synergistic marriage is not realized fully with a small battery.

Let's exaggerate this illustration.

Let's make the battery as small as a conventional car battery.. What would be the mileage of the prius then?

A larger battery means longer driving without using gas because all the kinetic energy we're LOSING NOW " would be utilized instead.

There is no one out here that can tell me that they don't waste most of their kinetic energy because the battery is already full!

The ice charges it up when warming the car as well as for the fun of it to preserve the longevity of the nimh battery as it doesn't like fill charges or low charges... You only get to use about 60 percent of what you have and that 60 percent just ain't much.

 

Of course if you charge the battery from the wall, if not then you have done nothing. We are not talking about plug-in are we? We are talking about regular Prius with li-ion.

 

Right, no plug in but rules do apply to both cars

 

If you live in a hilly area you'll have plenty of regen charging the battery, if you live on a flat plain not so much, either way a higher capacity battery at the same or less weight would improve the MPG of even a non plug in prius.

The least efficient mode for the Prius is when the gas engine is running below ideal RPMs. With a higher capacity battery you can run the gas engine at ideal RPMs for a shorter period charging the battery more, then shut off the gas engine. More battery capacity equals less gas used (assuming you don't have to haul more weight to get the capacity).

Take the 2005 Prius, replace the battery pack with a higher capacity pack that weighs about the same and MPG will increase. The 2010 Prius changed the gas engine more than the battery, essentially the 2014 Prius has the same battery technology that existed in the 2004 Prius. There is room to move to a higher density battery pack without increasing weight and still increase MPG.

 

What about the Prius C? Rated better city and I can attest to that. I get excellent mileage in the Prius C I'm borrowing. It's pack I think is 75% the size of the regular (maybe less? I do know it's smaller though)

 

I disagree with the arguments that a higher capacity battery (all else being equal) will improve fuel economy in a hybrid enough to be worth the cost. I admit that is a bit vague. The only independent work I have read regarding this question came from Wayne Brown, who added capacity to his G2 Prius. He lives in Texas and (I think) has mostly flat driving. IIRC he reported improved fuel economy, but not enough to pursue the topic as a practical matter.

Then we have the PiP. Admittedly it is heavier than a regular Prius but not by much. We could ask owners, but for one good indication we can just look at the EPA rated fuel economy in 'charge sustain' mode. IIRC it is about the same as a regular Prius.

 

Well now you're getting into a different argument... The cost! Lol!

Most non hybrid users think we're crazy in the first place because the extra cost isn't warranted unless you keep it for over 6 years and actually use it.

I just tell them "you're gonna pay somebody, ExxonMobil or Toyota, take your pick"!

I'd rather pay Toyota and take my lumps up front and enjoys years of awesome gas mileage with peace of mind.!

 

I looked up the EPA ratings.

Prius is 51/48
PiP is 51/49 if petrol only.

By the way Windstrings, welcome back. Glad to hear you have been busy (buying hybrids, that is)

 

Thx, been very active on RDF Forums.
Pip weighs a little more and more horsepower, they both are engineered on the brink for battery size, both waste lots of kinetic energy still.