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George S. Bower : I am confused as well. Is the exhaust heat first go into the ICE cooling liquid and then into the Cabin or does the exhaust heat go right from the exhaust to the cabin in a hot gas to air heat exchanger.


I didn’t think gen2 Volt had the EGR heat recovery on it either…….but not sure on that.
JeffN asked me to post this as his post is stuck in moderation

JeffN quote:

"There seems to be some confusion about Exhaust Gas Recirculation (EGR) vs Exhaust Gas Heat Recovery (EGHR). These are two completely independent mechanisms.

EGR (cooled EGR) takes some of the exhaust gas, cools it down, and recirculates it back into the engine's air input manifold. I'm not an expert on this, but my impression is that it helps reduce Nitrogen oxide emissions and also helps reduce engine pinging by slowing down combustion in the cylinder. This feature is present in the Prius, the 2016 Volt, and the 2016 Malibu.

EGHR is a completely different mechanism. Optimum engine temperature improves engine efficiency and gas engines in full hybrid cars are frequently starting and stopping which causes engine coolant temperatures to drop below the ideal level. The exhaust heat recovery feature helps the engines quickly recover to their optimal temperature when they restart during driving.

Basically, the hot exhaust is run through a heat exchanger — sort of backwards from how the engine radiator or the cabin heater core works. Once the engine coolant reaches the optimal temperature there is a valve that causes the already hot coolant to bypass the exhaust heat exchanger. This feature is present in the Prius (since 2010) and the 2016 Malibu but is not present in the 2016 Volt presumably for cost reasons."
 
Thanks for the very informative writeup! You answer several of my many questions regarding the 4th gen Prius.

There was a lot of talk online a week ago about if the "Eco" model was indeed a higher MPG model or just the stripper Prius. It seemed it could go either way. Pictures of the Eco had smaller wheels and tires ( which naturally would mean slightly more MPG ), plastic hubcaps and no fancy "Storm Trooper" glossy white plastic on the center console, plus fabric seats. It doesn't really mesh that the cheaper model would get a more modern lithium ion battery pack, though...

I know I'm not going to buy one. Over at PriusChat they're chortling about Mr. Ruess' comments about 2nd gen Volt leapfrogging Prius. Even the first gen Volt did that - It just was priced a bit high, and GM has a long legacy of bad PR to overcome.

The styling of 4th gen Prius is awful. I mean, appearance is subjective - but nobody likes this. This was the redesign after Akio Toyota - CEO, sent it back to the drawing board to make it "sportier"!!!
Ugh! What a hot mess. The headlights look like jagged shards of glass - the upper model gets nice wheels, but the lower option levels get the tiny Prius wheels ...Those C pillars ( the vanishing black ones ) just stink it up even more. The rear end looks like a regular Prius if you were on LSD.

Most interesting to me will be gen4 Prius' handling. The independent rear suspension, lower center of gravity and more forward position of the battery pack will definitely improve on the current horrible Prius' dynamics. Will Volt's heavy battery and same as gen1 twist-beam solid rear compete? We shall see. I know Prius couldn't have gotten much worse, and Volt has a solid ride, if not sporty handling in the twisties.
 
James :

There was a lot of talk online a week ago about if the “Eco” model was indeed a higher MPG model or just the stripper Prius. It seemed it could go either way. Pictures of the Eco had smaller wheels and tires ( which naturally would mean slightly more MPG ), plus fabric seats. It doesn’t really mesh that the cheaper model would get a more modern lithium ion battery pack, though…

Good input James. I thought the ECO model meant Li batts as well but it seems not necessarily


James :

The styling of 4th gen Prius is awful. I mean, appearance is subjective – but nobody likes this.

I don't think anybody liked Gen 2 or 3 either.


James :


Will Volt’s same as gen1 twist-beam solid rear compete?

Good comment James. The Volt handled much better than our Gen2 Prius but I had forgotten about that rear end suspension in the Volt. I remember looking at it under my car and thinking how basic it was. Definitiely not a trick rear suspension IMO.
 
GM created Volt based on want. Executives & Enthusiasts expressed their desires and many were fulfilled. It was an engineering achievement worthy of praise. Awards were presented. Celebrating lasted for awhile. Then, reality set it. There was recognition that business need had been sacrificed. No worries. Gen-2 would address the goals which remained outstanding. All we had to do was be patient.

To everyone's surprise though, the plan changed. Volt would remain the premiere vehicle it was designed to be and other vehicles would satisfy need instead. Suggestions to diversify would be taken, the very approach which had been strongly outspoken against would now become the plan. Rather than focus entirely on a single solution, Volt would be complimented by an EV, a plug-in hybrid, and a regular hybrid.

Toyota stayed true to business need. That's why Prius was constantly the source of comparison. Even though Volt was declared "vastly superior", it could never escape being compared. And now that details of gen-2 plug-in Prius are being revealed, Volt enthusiasts are doing everything they can to avoid discussing it. That's quite telling.

Stop only including the regular Prius. How could that possibly help Volt? GM's own offerings... Bolt, CTS plug-in, and Malibu hybrid... will get more and more attention if that type of misleading continues. People will see the omission and move on.

There's want & need, two very different things with very different priorities. No amount of spin will prevent the facts from being discovered. Let the data speak for itself. Geez. Different people have different priorities. But one thing is the same for all, the business must sell vehicles in high-volume at a profit to continue paying the bills. That's paramount above to want. Need always wins in the end.
 
One of the key technologies used by the Prius, and initially reported for the new Volt is externally cooled exhaust gas recirculation. EGR has been around since the 70's to help reduce NOX emissions but should not be confused with this new variation as the main purpose for this system is improved fuel economy.

Here's a link to an article discussing how externally cooled EGR is implemented and the benefits that can be obtained by implementing it.

http://www.swri.org/3pubs/ttoday/Summer10/PDFs/Clean-and-Cool.pdf

There are those that say improved fuel economy in the Volt provides little benefits in real world usage. They would be absolutely correct as we Volt owners know. But how can GM convince the general public that a Volt is a better proposition than the tried and true Prius? The biggest claim to fame the Prius has is its fuel economy, if GM could close the gap, I think more people would be willing to consider the Volt and when they finally figure out what it can do for them, many will become owners.
 
We have a 2014 Prius V that we purchased last year because we needed a larger vehicle for family trips and outings. If there was a Voltec option in that size, we would have gone for it without hesitation because we absolutely love our 2013 Volt. The kids much prefer the Prius V because it has so much more room in the back seat. We did a 5000 mile trip this summer to Yellowstone and with the car completely packed with gear and mountain driving and the 80+ MPH driving across Colorado and Wyoming, we still ended up with a 43 MPG average for the trip. My main irritation with the Prius is the EV mode is completely anemic. You can't accelerate at all (not even normal acceleration) in EV mode or it turns off. There would be a lot to gain in MPG if they had a usable EV mode. I'm very curious about the 2016 Malibu Hybrid's EV mode performance. Hopefully it is more like the Volt which would help it compete favorably with the Prius. GM....please design an Voltec family vehicle !!!
 
ddorrance : My main irritation with the Prius is the EV mode is completely anemic. You can’t accelerate at all (not even normal acceleration) in EV mode or it turns off. There would be a lot to gain in MPG if they had a usable EV mode.

You just described the PHV model. Having a larger battery-pack and plugged-supplied electricity increases EV power quite a bit.

I climb steep residential hills and accelerate onto the local highway (55 mph) without triggering the engine with my 2012.

Here's my stats: 65,124 miles; 890 gallons; 5,535 kWh; 73.2 MPG. That's 3.5 years of ownership in Minnesota, where winters are quite harsh. So as you could imagine, that 9% increase in hybrid winter-operation efficiency from gen-4 will be a nice upgrade.

Also, note that the gen-2 PHV will raise the top EV speed from 100 km/h (62 mph) to 110 km/h (68 mph). Above that speed, you'll still have the boost (electricity being used to allow the engine to run at a lower RPM for better efficiency).
 
My biggest problems with the Prius are all still there:
- NiMH batteries (even if the Eco will finally offer Li-Ion, NiMH shouldn't be used at all)
- Weak handling and performance (if you love driving, a Prius is not where you want to be)
- No all-electric mode for most models

Point 3 is really my biggest beef. Even the Plug-in version has extremely limited range, and doesn't work much above 60 before kicking in the gas. I believe we need to distance ourselves from fossil fuels as much as possible, and that the Prius is not a positive step in that quest.

With my Volt, I'm able to do around 90% of my driving without using a drop of gasoline, and I find that a step in the RIGHT direction. If I could afford a Tesla, I'd probably go that route, taking a further step. However, simply improving the efficiency of a vehicle that must have gasoline to run, is not helping us as much as alternative options out there (like the Volt, depending on your situation).

Yes, greater fuel efficiency means less gas used, but you're still dependent on it.
 
The Q : Point 3 is really my biggest beef. Even the Plug-in version has extremely limited range, and doesn’t work much above 60 before kicking in the gas. I believe we need to distance ourselves from fossil fuels as much as possible, and that the Prius is not a positive step in that quest.

65,124 miles; 890 gallons; 5,535 kWh; 73.2 MPG.

Eliminate the plug-supplied electricity from that real-world data:

65,124 miles; 1,302 gallons; 0 kWh; 50.0 MPG.

That's 412 gallons not consumed. How can that not be considered a positive step?
 
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