POLL: Which of these fuel-efficiency improvements do you expect to see in the Gen IV?

Thanks for the detailed response. Your analysis seems reasonable to me given the short commute daily duty you use it for, if the choice had been between a LEAF and a Prius. But you already own a Prius, so I don't follow why you spent another ~ 9K USD to save about 64 cents a day.

 

2016 i suppose.

 

The concept is this. I'm in a two person household and I'm the primary wage earner.

The nicest car is mine if I'm commuting and hers if I'm not. (2012 Leaf)
The 2nd nicest car is hers when I'm in car #1. (2005 Prius)

this leaves me with an older car to sell which is a 1998 Saturn SL2 with AC that doesn't work. It was just plain time to upgrade the fleet and do the hand me down.

So the choice was what car newer than the 2005 Prius to update the fleet with? Another used Gen II prius? A used Gen III Prius? A used Leaf? I couldn't find a PiP cheap enough and the Leaf worked out to be the best deal I found.

My thought is I'm going to either have to pay tons to keep a beater going or I can pay a hair more and grab a more reliable car.

I got the Prius when I did because it was more reliable than the Saturn and cheaper per mile to run and had more luxury features than our late 90s beater.

I got the Leaf when I did because of more of the same, better than both prior cars, cheaper to run than both prior cars, more luxury features than both prior cars.

In fact the telematics (remote charge status, remote charge start, remote climate control) and the heated seats/steering wheel were features I couldn't find in a Gen III Prius.

 

There is a new area in which we might see performance gains: Combustion cycle change. Many of the new motors from Toyota (5.0 in the RC-F, 1.2T in the Auris and 2.0T in the NX) can change between Otto and Atkinson cycles.

Imagine if Toyota introduces this technology to the Prius. It could then achieve an even better emission by a utilizing an even less powerful, but more fuel efficient or clean Atkinson cycle. The press and lead footed drivers will be happy by changing to Otto-cycle when required. The combined output will now become roughly the sum of the normal Otto cycle 1.8 liter engine (~134HP) and the output from the battery.

Combine this with weight savings of at least 5% and you suddenly have a car that accelerates from 0 to 60mph in 8.5 seconds or less! I'm keeping my fingers crossed!

 

i wonder how governments would measure fuel efficiency?

 

One car. One engine. Two combustion cycles. Like a switch. Using one combustion cycle when it is preferred, then the other when that is preferred. Like the new engines from Toyota that I mentioned.

The current Atkinson-Prius is on par with normal Otto-1.8 liter engines because of the hybrid system. By using an engine that is able to shift between cycles (such as the other new Toyota engines) it can gain both fuel economy and performance.

 

I agree it will gain performance, but I don't see it gaining economy. It could actually lose it.

The Atkinsonized cycle is trading power output for fuel efficiency compared to the Otto. Being able to switch between the two on an ICE car gains economy without losing the performance; since the Atkinson mode is fine for the majority of driving tasks, and it can go Otto for those fewer high power demand times. A hybrid like the Prius just uses the electric motors to supply any high power demand instead.

Being able to go Otto will further increase power output, but now the hybrid is trading the economy of the Atkinson cycle for the power of the Otto. So performance goes up while fuel economy goes down.

Now if you are also thinking of further downsizing the engine by using this technology, it might give better fuel economy while maintaining the performance level. If so, then it becomes an issue of cost. Being new, the wider valve control does cost more.

 

that's why his first sentence is, 'there is a new area in which we might see performance gains'.

it's a bit confusing, being in an 'fuel efficiency improvements' thread.

 

I agree with Trollbait and Tideland Prius.

The Otto/Atkinson switch was probably targeted at conventional engines essentially as a means to reduce waste when demand is less. It is probably less likely to be useful in a hybrid to do the opposite i.e. supplement power demand by switching from Atkinson to Otto. I say "probably" because I am no expert. Ultimately, I guess these decisions come down to cost vs. benefit i.e. is it more cost effective and better engineering to improve power demand in a hybrid by improving the electric drive side of things or is there still a benefit to be had getting the ICE to also switch cycle.

We already know that G4's ICE efficiency will be better than G3's. That coupled with reduction in weight (and possibly wind drag) will contribute significantly to highway mpgs and somewhat towards town mpgs. If Toyota can recover more energy and have a bigger capacity battery AND the ability to recover/release battery energy quicker (higher capacity motors/generator and improvements to HV infrastructure and battery to allow higher current), that will mean the ICE will be used less and that will contribute to town mpg improvement and highway mpgs somewhat. So essentially the Prius was already ahead in all these aspects.

Add to this, I am hoping there will be improvements to cabin heating efficiency. Who knows Toyota might even have a surprise for us in the way of supercaps or SiC but less likely.

 

You should move to Wyoming! We leave our keys in our unlocked cars almost all of the time. We leave the engine running on grocery trips when it is very cold.

 

^But those winters!