How will the Chevrolet Volt be better than a Toyota Prius plug-in hybrid?

The Atkinson cycle trades power for efficiency. It sounds like the current engine has the right blend of attributes. Perhaps it can work, but, working in the confines they likely had, it would have meant using the 2.0L block. Improving efficiency is nice, but space and weight have a higher priority than in a non-PHV or traditional vehicle.

Yes, but until I heard hype on the Prius EGR, I assumed everybody did this as matter of course. Why would they not? I think my B&S lawnmower has a real basic system. Does the Prius system do anything with it that the others aren't?

Good question. Since we don't even get the plain A1, it's kind of moot for the US right now.
Might not matter anyway. The Wankel may not make it to the production model do to development cost. It's a shame if so. I don't see how they'll retain the cargo and passenger space of the non-hybrid with a piston engine as they can with the rotary.

And it does it on regular gas, for those in which it matters.

 

I was countering the claim that gm did everything about efficiency. The trade off isn't weight though its cost and development time. The Mazda skyactiv 1.3 L using electronically controlled input valves, higher compression, and DI will run in atkinson mode and has more horse power than the gm 1.4L engine. The nissan 1L miller cycle engine is another example that is closer to the original volt desired engine.

Not trying to put any hype in here. Old egr systems were about lowering pollution not increasing efficiency. There is nothing magic about the toyota system, but it does increase efficiency, cost, and complexity.

 

I presume those numbers assume a trained, professional race-car driver at the wheel to accomplish optimal shifting. With the Telsla, you just put the pedal to the floor and hold it there.

But I'm surprised by those numbers.

And the Tesla does it with domestic electricity (clean hydro, in my case) and no exhaust.

 

For acceleration/$ its hard to beat the vette. I would not put much worry in the driver, on the street there are few places where you are going to drive sub 4 acceleration to 60.

Also in the discussion should be the boxter spider which is a couple of tenths slower but is one of the best handling cars out there. I would be quite surprised if a tesla driver would use all the fingers on a hand to count the number of times they accelerated faster or took turns faster than in a boxter spider, a car that costs in the $60Ks.

But the tesla is about uniqueness and people pay tens of thousands for tenths of seconds even if they don't use them. There are plenty of boxters and vettes out there and they all use gasoline. Porsche will likely give us an electric boxter based on the tesla roadsters success. The key advantages are the plug instead of the pump and the feel of torque in a single speed transmission. I can't agree that the roadster nor the volt nor leaf are overpriced. They all are fairly unique in there segments. That doesn't mean I expect any of them to sell like a F150.

 

I don't think automatic Corvette's numbers are that far off.
If you want a high performance car, it is a good value.

 

Z06 is a fun car, and excellent value for the dollar. Especially if you get a good used one.

I had DI on a Mazda and liked it. That little 4 cylinder was pushing 290hp, and was borderline rediculous. Not to meant it got pretty good fuel mileage. Is kind of suprising that almost 6 years later you still do not see DI on many vehicles.

Here in Jacksonville, FL it does get quite cold (I know you are up in the Northwest where it gets extremely cold, but I am now acclimated to FL). I am moving to Norfolk, VA next week so the heater will be even more important then. I guess you can say I am weak. I have never liked the cold much. When riding my bicycle in the winter time I would be in multiple thermals, sweat pants & shirts, and have my face mask. With it being in the 50's/60's lately have felt like it has been freezing. I think it was the week after we picked up the Volt that we had that cold front rolling in and my god it hit me like a brick wall when I opened the door. I just bundle up. If I were staying here in Florida, and knew I would be here forever I would have most likely bought the Leaf as I have always lived close to work since 2008 when I started riding my Trek to work.

I agree with you though about people choosing to live far from work. Some people at my work live up in areas of southern Georgia, or farther south past St. Augistine and all.. Then they complain of being tired, and spending X money on gas. Granted I used to waste gas all the time with my Hemi, and looking back I realize how stupid it was throwing all that cash away to burn it for the "cool" factor. Personally never heard of this Xebra you keep mentioning, but I applaud you for sticking with it and making it work. It obviously paid off seeing as you have a Tesla Roadster now.

The next evolution in EV's should probably be adding a transmission. I know Tesla tried, and kept breaking them. Being a small company that took a huge risk I imagine they did not want to squander money on something they were unsure of, and focus on building a solid vehicle to sell which lead to the transmission idea being shelved. Think even if we had just a 2 speed like what they originally were proposing we could possibly get a decent gain in range without really changing much of anything.. Unfortunately it must be both light and strong which means it will be expensive. Probably something like what we have on the helicopter with a magnesium casing, and hardened steel internals.. About the only thing in my mind that could handle the instant torque load.

 

80% acceleration up to 90 MPH and compare RPM of diff vehicles

While 80% acceleration up to 90 MPH is not a regular use of most car this is just a test and comparison to show how the Volt operates in comparison to other vehicles.

In watching videos recently I really liked the comparsion chart showing the RPM off the Volt's ICE.

My point is just how the Volt works and not comparing it good/bad to the prius king MPGs just to head of those post.

Clearly it shows how they repurposed this 1.4L ICE and were worried about noise, vibration, and harshness (NVH) even with 'hard' acceleration. I edited the photos to put the legend within the chart.

This first graph show ICE/Gas_generator while in CD (Charge Depleting battery only mode) -- yes 0 RPM and the orange line. 90 MPH @ 80% pedal acceleration and NO ICE.



This 2nd graph show ICE/Gas_generator while in CS (Charge Sustaining mode) -- yes 3300 RPM compared to 4800 RPM self-imposed limit -- BUT compare it to the other cars!!!
Notice even at 80% acceleration that the ICE isn't coming on until 20 MPH. They said if you accelerated less it would take longer. Compare to the Fusion and other listed vehicles (hybrids) and how their ICE comes on almost immediately!!

 

You brought it up in '09. Here,
here, and here.

 

Scott, 80% accelerator is rarely used in typical drives. In the test cycles from Japan, Europe and US, anything more than 30kW (40hp) is rarely used. That's why hybrid car battery power is intentionally sized that way.



In your second graph, Volt used little (about 1/3?) energy from the ICE. The rest must be from the battery. Out of all those cars, Volt weights the most (~3,800 lbs) and ICE (1.4L) is the smallest. There is no way the battery charge is sustained after 80% pedal acceleration.

Volt's ICE will need to recharge the battery pack later on, running the gas engine 2x longer than Prius or the Fusion hybrid. That graph doesn't show the rest of the story.

Regarding the first graph, Volt has a powerful (111kW) electric motor and the battery pack charged with external energy (from the grid). Yes, it can keep the engine off when using the external power. None of the car on the first graph get the external power. They are simply using all of the on-board energy. Note, Volt is the only car that has half of it's powertrain (ICE) disabled. The other half carries it's weight.

In summary, the graphs tell the same Volt marketing story. Volt's primary power source is electricity yet it's performance is measured with gasoline (engine) usage.

 

On various ICE efficiency "tricks", I've posted a number of these before but a few thoughts:

- The maximum fuel->battery efficiency occurs at about 2800rpm/Wide Open Throttle. Anything else is a compromise for NVH, warm-up, whatever.

- It runs very close to WOT all the time. In fact, what looks like "close" to WOT is effectively WOT at lower RPM. There's no pumping loss advantage to opening the throttle more, so they don't.

- The fuel map has no extra WOT enrichment. It doesn't need it.

- They can run aggressive timing because the engine has no driver-dictated response requirements. When he/she floors it, the electric motors provide the propulsion and the ICE catches up to demand in due time. This is true even in the "direct connect" mode since the ICE and MG2 are load sharing.


Of course, so many of us rarely use the ICE but it's interesting to the nerds (raises hand) to learn what it's doing.

 

The title of the market campaign has been "GALLONS SAVED".

We've seen that before. It was a different technology, but was promoted the same way... to end our dependent on oil. It too used electricity instead of gas. But rather than transport the electricity as is, it was converted to hydrogen.

Remember fuel-cells? There was no regard to how much electricity was actually being used. They just pointed out the efficiency improvements from each generation of stack. The gas equivalency was horrible. So, they simply didn't mention that in the advertising.

How's that different from the current "energy efficiency" reports just showing a rate, not listing the amount of kWh actually consumed? Instead, there's a "gallons saved" value.
.

 

The same with my Gen2 Prius. When it is making 9.6 hp revving at 1,223 rpm, the load is 79.2%.



The ICE in Gen3 Prius and PiP are supposed to be more efficient at even lower power demand. That's ideal for PHV application where more battery power can be blended in.

 

I actually didn't buy the Tesla for being a sports car. I bought it for being electric, after the Porsche conversion flopped and Nissan kept screwing up my order for a Leaf. Acceleration/$ means nothing to me when it means burning gas. If I MUST burn gas, I want the most efficient car I can get, and that's the Prius.

I will give you this: The electric Porsche 911 Carrera handles better and takes turns faster than the Tesla Roadster. But the Tesla is no slouch! The Porsche is heavier, and that helps it hold the road in fast turns.

Again, for me it was not about the uniqueness. It was about the electrons.

Yes, it's true. "Hot" and "cold" depend a great deal on what we are used to. One day in Mexico when it was in the upper 70's and I was sweating in shorts and short sleeves, a classmate arrived in sweat pants and sweatshirt. I asked her about it, and she told me "Where I come from it never gets this cold." She was from coastal Oaxaca where 80 degrees F. is cold. And a literary example: the writer Juan Rulfo says of a region of Jalisco that when the campesinos die and go to hell, they come back for their blanket.

Three wheels, 35 mph top speed, all electric; made in China and imported by ZapCars in California. I think they are no longer importing them. It's a klunky little car, really not well designed or well built, and yet it gave me 4 years of reliable daily transportation.

I disagree. The 2-speed transmission would not improve range. What it would have done was give the car even greater acceleration at the low end, and higher top speed at the high end. Range is basically dependent on battery capacity, total weight, motor efficiency, and aerodynamic drag.

I apologize. I had forgotten saying that. I did predict that GM would never market the Volt, and I was wrong. On the other hand, the "Volt" they did market sure falls short of what they were promising back then. Well, I did eat a chocolate bunny on Easter 2010, and will eat another on Easter 2012. I missed this year due to my diet. And I didn't say WHEN I'd eat the chocolate bunny.

 

The Volt hyped was:

• Under $30k
• 40 miles EV range
• 50 MPG after
• AT-PZEV tailpipe emission
• 10 years / 150k miles battery warranty
• Gas engine is just a range extender - won't connect to the wheels

None of the goals made it to the production model.

 

I think in some of the discussion here there is a feeling that there is a total amount of BTU's available, and it doesn't matter whether they come from petroleum or electricity, whatever uses the least BTU's is best.

I disagree with that. I don't need a new benefit in BTU's from using electricity. I think its good to compare effects of the higher BTU cost, like total emissions and effects on air quality etc... But the truth is we have an endless renewable source for electricty that is not available for oil. If I generate 40 kwh in a day on my roof and use every bit of it for my driving, I don't care that I used a lot more power than in the 1 gallon of gas I otherwise might have used. Even though burning the 1 gallon might have meant fewer BTUs consumed, it would still be worth it to me to not burn it.

Gallons saved is the relevant metric for my concern.

 

Not the Gen I anyway, I think they're still working on it, but in the meantime I'm grateful for the opportunity to drive what they did get to market which is a fine automobile.

 

• Under $30

They were always cagey about whether their numbers were before or after tax credit. Even after the credit the MSRP is a bit over $32,000. On the other hand, the PiP is also higher than what many expected.

• 40 miles EV range

They achieved 52 miles of EV range if you count it the same way people count the 14 miles of EV range on the PiP.

The EPA range is 35 miles but 40+ is easily achievable in real use. I get 45+ miles of range on a daily basis during most of the year.

• 50 MPG after

This number first came up when they were talking about using a 3 cylinder 1.0L engine. Who knows if that was ever realistic. When they shifted to using the 4 cylinder 1.4L the few times they mentioned MPG in Q&A settings they talked about 50 MPG as being a target or goal. They clearly missed that target by a wide mark. Nonetheless, the Volt still gets among the highest mileage (within top 10) of all the 100+ mid size and smaller cars sold in the U.S. market. Of course, if you are using a Volt as it was intended, the mileage difference does not add up to that many more gallons at the end of the year.

• AT-PZEV tailpipe emission
• 10 years / 150k miles battery warranty

They missed achieving this the first year or so but both of these are claimed for availability within 2-3 months after the PiP becomes available next Spring.

• Gas engine is just a range extender - won't connect to the wheels

Who cares? Yes, this was bad PR and marketing but to customers this is completely undetectable (unlike a Prius at slow speeds) except under unusual circumstances (suddenly flooring the accelerator at highway speed has a momentary pause similar to a gear kick down in an automatic transmission). It increases efficiency in both EV and hybrid modes by providing a CVT at speeds above 40 mph or so. That's really a previously undisclosed feature.

 

I consistently achieve 40+ EV miles unless I travel on JTB/9A/I-95. I know that will not be the case in the winter time, but hopefully will be over 30.

Suppose maybe you are right about the transmission thing though. I look at it from the perspective that if you leave the original gear the same, and then give it a high second gear to reduce the RPM that it would help it go farther. I am sure at higher RPM's with the 1 gear it creates tremendous amount of heat as you approach max current loadings. I am pretty knowledgable with full mechanical vehicles, but I do lack quite a bit of knowledge when it comes to electronics. Is why I became a structural/hydraulics mechanic and not an avionics tech. Guess that is why we are all here though. Pool our knowledge and try to figure out what we can.

 

Compared to what?
.

 

My last car was a prius, so compared to that.