GM wants a 230MPG rating from the EPA

Here we go again. The Volt has a 150hp motor. The gas generator (genset) is 74hp. So for 0-60 you have 150hp. Sure, you cannot keep up 150hp CONSTANTLY but that is not a realistic need. When have you had your Prius or any other car floored for more then 60 seconds at a time?

During normal highway cruising (after you are low on battery) you will be using less then half of the 74hp. The rest is going into the battery. Passing will be fine. Even long hills will be fine.

Again, on engine and motor sizing Chevy has it right on the Volt. Bigger would be just wasteful and make lower mpg. This is not a sports car. Its performance will be similar (within 20%) to the Prius.

[ame=http://en.wikipedia.org/wiki/Chevrolet_Volt]Chevrolet Volt - Wikipedia, the free encyclopedia[/ame]

 

Has everyone completely missed the fact that the Volt will have regenerative braking as well as the "range extender" (gas generator)?

So if you're using the brakes you're recharging the battery just like in the leading hybrids. And yeah, I get it, regen only goes so far, but it would potentially mean that the 40 miles could be greatly extended before the gas generator even comes on, which is at like 30% state of charge if I remember right.

The Volt gets an AT-PZEV rating, something this entire thread seems not to have mentioned.

There's a LOT of info here: [ame=http://en.wikipedia.org/wiki/Chevrolet_Volt]Chevrolet Volt - Wikipedia, the free encyclopedia[/ame]

 

Aero drag can be made similar to the Prius. However, Volt has these two disadvantages of a series hybrid architecture:

- All energy from gas engine has to go through conversion loss.
- Heavier battery (~300 lbs more)

Prius is a series-parallel split hybrid so it has the advantage of direct mechanical power to the wheels. On the highway, most of the power from the ICE goes through the mechanical path. This is not possible with the Volt. All the ICE energy has to be converted to electricity and charge the battery first.

Heavier car will require wider tires and more robust suspension to support it's weight. Both of these will lower the MPG.

The advantage of a series hybrid over the parallel is that it doesn't need a transmission so there is no additional power loss. Prius doesn't have a transmission either. Prius achieves this by the ingenious use of the power split device. It uses the electric path for low gear and mechanical for high gear. Any variable "gears" in between is how the computer split the power to either ways.

Having advantages of both series and parallel designs made HSD unparalleled in a series of driving conditions. Honda IMA (parallel) hybrid can not match HSD even with the lower price advantage. It turns out there isn't much of saving after all.

Plug-in series hybrid (Volt) is more expensive due to exponentially higher cost of the electric powertrain, controls and battery pack. Volt's has e-motor and generator twice powerful as the Prius. The battery pack holds 16x more energy. $20k premium price will come down with mass production but as to how much is the question. Will the extra cost worth the benefit? It will be interesting to find out. My guess is no but the market will decide that.

There is one way to reduce the electrical demand in the plug-in vehicles... just let the gas engine assist for peak demand and heat. This will enable smaller battery pack. Looking at one year data of The Force's hymotion plug-in, PHEV Prius use about 145 Wh per mile. Volt consumes 250 Wh per mile. The 40% difference can be made to go further or cost less. This is just by using the gas engine already in the car. Volt does not take advantage of this but the PHEV Prius does. Why? The reasoning behind it is very simple and silly. It is because Volt is an electric car. Gas engine is not supposed to power the wheels but only to recharge the battery. We'll find out in the future if taking the 40% disadvantage simply to call it an electric car was the right decision or not.

 

Remember even when the Volt battery is drained, it still has 5% SOC buffer range to assist in acceleration. Therefore, it won't suffer as much as you think but it should be noticeable due to lower voltage of the battery.

 

That's been my concern also. The vast majority of people only own one car. There are few people (compared to the global auto-buying population) that have more than one car. So, in considering the Volt, consumers are going to consider what happens if they go on a road trip, or heck, what if they just happen to forget to charge the car? Case in point, I went on a road trip this past weekend with my friends, 712 miles round trip. In my Corolla, I filled up when I left my house, and I filled up half-way on my way back. With the Volt...I might not have made it from one gas station to the next, and that would be a BIG problem. Wait until the news media gets a hold of that - 'family stranded in middle of desert when Volt can't make it from one gas station to the next.' It won't matter if GM says "the Volt wasn't designed for that." The media will have already done damage to the image of the Volt. Heck, if I'd had a Prius, I might have been able to make a round trip on the same tank. Now, I must acknowledge, that 95+% of the mileage on my 117,000 mile Corolla is daily commuting, and the 40mile EV would suffice for the vast majority of that; saving America from foreign oil.

So what's my point? What is my suggestion? Looking at vehicles from a purely efficiency standpoint, hybrids (Prius) use about half as much to one third as much energy as a traditional car, regardless of whether it is gasoline or electric. So, regardless of whether the main energy source is gasoline, electric, or whatever, by simply implementing a regernerative braking system into all automobiles, and increasing efficiency, we can increase mileage and decrease global energy demand from automobiles by one half to one third. If the Prius can squeeze 50 miles out of a gallon (EPA standard test), shouldn't the Volt be able to match this 50 miles per gallon after the EV runs out (heck, they've been "developing" and "refining" the Volt for how many years now?). After all, this is GM's "revolutionary vehicle," isn't it? If Toyota dropped a Volt-sized EV into the Prius and it performed a 40 mile EV range, then the Prius would still perform 50mpg in hybrid mode after that. Shouldn't we expect that the Volt can at least get 40mpg on gasoline only?

 

It is anticipated that the Chevrolet Volt will be granted a California Air Resources Board (CARB) classification as an Advanced Technology Partial zero-emissions vehicle (AT-PZEV).

EPA said they haven't test the Volt yet and backing away from 230 MPG claim. So they won't know how Volt's tail pipe emission will be once the battery pack is depleted. I don't see any reason why it can not achieve AT-PZEV but that rating requires 10 years / 150,000 miles warranty from the battery pack.

 

It is unlikely that the Volt's gas engine will use Atkinson cycle (to gain 15% higher efficiency and lower emission) because it is patented by Toyota (6,848,422). Unless GM use HCCI, I don't see how they would get 50 MPG in charge sustain mode.

 

The Volt has the advantage of a gas engine dedicated only to generating electricity. It can be tuned to a higher efficiency and a lower range of rpms. The efficiency of power electronics has gone up past 95% now, and the power loss due to conversion is less important.

I love the Prius PSD, its just an amazing way of dealing with a complex problem. Its very efficient. But the Volt has just a single speed ratio with even a simpler fixed gearing system. There is even less loss here then the Prius.

The Prius and Volt each have thier own advantages and shortcommings. The Volt is not going to be for everyone but its going to be a DRIVABLE CAR that gets great mpg. I am just always surprised how negative people can be about another choice if its not made by Toyota.

Will I get a Volt? Probobly not. The Prius with an aftermarket plug in kit will probobly do best for me at a lower cost as my commute is just 14 miles now.

 

That patent is not for the Atkinson cycle engine. That was created in the 1800's and is well out of patent. The patent you mentioned is for a control system needed to reduce knocking and increase efficiency on an Atkinson cycle engine operating under many speed and load conditions. The Volt won't need that to do Atkinson cycle on its genset. I am not saying they use Atkinson cycle, that data has not been officially released.

I too would imagine they would need it to get to the efficiency they need.

Control system and method for ... - Google Patent Search

 

I have no problem buying from GM, but neither GM nor Toyota offer my ideal car at the present time (2009/2010). My ideal car right now (2009/2010) would be a real hybrid; meaning that 50% of it's energy would come from gasoline and 50% of it's energy would come from an electric power cord. Think of it as a PHEV Prius that does not have an EV-only mode, but rather uses the electric motor every time you are accelerating, whether you are going 5mph, 35mph, or 55mph, and the amount of power the motor would contribute would be greater than the current Prius. Since the electric motor would be doing all of the acceleration (in addition to the engine providing power required to maintain instantaneous speed), the gas engine would only need to be a 1.0 liter. The gasoline engine would only have one function: maintain speed at whatever speed the car is traveling at that moment. The electric motor would fulfill all acceleration requirements beyond the engine's power at the instantaneous speed.

 

Peak efficiency of the Otto cycle is about 15% less than peak Atkinson cycle. Although Prius ICE does not have the freedom of the genset, HSD with the support of the HV battery can keep it at peak most of the time. Therefore, HSD also inherit this series hybrid advantage.

15% disadvantage of 50 MPG is 42.5 MPG. If conversion loss is 10%, it would be 38 MPG. Would buyers be happy with it when they find out? They would be already expecting 230 MPG from the way it was hyped up.

 

Ford and Nissan license it. GM's two mode has some type of late intake valve closing but the result does look as good as with the Atkinson cycle, especially on the highway (low load).

 

I definitely understand what you are saying, and I thank you for bringing it up (I like to talk about regen braking). But, considering that GM likes to put icing on every press release cake that they bake, I tend to believe that the 40 miles includes the regen braking. I think it is pretty safe to say that if the regen boosted the range to 60 miles, GM would have ran to the media like a little kid and said "It gets 60 miles on a charge!"
I think it's safe to say that the 40 miles includes the regen braking.
Can anyone on here that is familiar with other EVs (Tesla, PHEV Prius in EV mode, other) enlighten us on the range of other EVs? Tesla would best since it also uses Li-Ion. Does anyone know the size of the Volt battery versus the size of the Tesla or PHEV Prius battery?

 

Again, that patent is not the cycle itself, its for technology related to putting it in an engine with many speeds and loads, avoiding knocking. The genset for the Volt should not need that technology to do an Atkinson cycle.

 

Volt: 16 [ame="http://en.wikipedia.org/wiki/KWh"]kWh[/ame] nominal, 8.8 kWh usable
Ev1 with best batteries: 26.4 kWh
Tesla Roadster:53 kWh
Prius 2004-2009:1.3kWh about half usable
Nissan Leaf:24kWh

 

Thank you.
How the ranges of the four vehicles compare:
Ev1 NiMH: 75mi - 150mi. (wikipedia)
Tesla Roadster: 244mi. (wikipedia)
Nissan Leaf: 100mi. (wikipedia)

I think the best comparison to the Volt in terms of energy is the Tesla since both vehicles use Li-Ion. Want to see magic? (8.8kWh/53kWh)(244mi)=40.5mi. I wonder if GM actually tested the Volt, or if they just used this calculation.(laughing)

The Tesla is more efficient than the Leaf though (not surprising since the Tesla probably weighs less than the Leaf). 244mi/53kWh = 4.6mi/kWh. And 100mi/24kWh = 4.17kWh.
An additional possibility for the difference is that "244" is obviously a test result, whereas "100" seems more like an estimate.

Bluetwo, based on these numbers, I think the Volt's claimed 40 mile range already includes energy from regenerative braking.

HERE IS THE MOST INTERESTING PART OF ALL OF THIS: The Leaf is estimated to have a price tag of $25K to $33K, which includes a 24kWh Li-Ion battery, yet the Volt, which only includes a 16kWh Li-Ion battery is predicted to cost $40K. Yes, the Volt adds a gasoline engine, but GM already knows how to make engines at a low cost.

 

Yeah, I'm surprised at how it was starting to feel like there was a lot of hate and negativity towards the Volt: something that could be a step in the right direction. Yes it's far from perfect but if we had a perfect solution we wouldn't still be stuck on foriegn oil would we?

Hontestly guys, sometimes it feels like it isn't enough that a lot of you already have the BEST hybrid out there, but you just can't fathom the idea of anyone else catching up. As though you would step on the head of someone who is trying to get up the ladder just for the sake of keeping that smug little feeling. Obviously I'm being sarcastic!! But don't make a bad image for yourself and the Prius by criticizing everything else to death.

 

Hold on a sec, I don't think Nissan specified a price nor whether it included the battery or not. They seemed open to leasing vs. buying the battery as well as the car. From searching the questions at http://www.nissanusa.com/leaf-electric-car/:

Regardless of the validity/methodology of GM's "230 mpg" claims, it definitely helped get them a ton of attention in the media and people/organizations talking about it. I wouldn't be surprised if there's plenty of talk at the water cooler about it.

 

it's because of their track record

It's because GM has had such a poor track record in this space. They had leadership w/the EV1 but killed it. They poo-pooed hybrids, Lutz called global warming a crock and then WAY LATE came out w/piss-poor mild hybrid vehicles that got little improvement, sold in tiny numbers and were discontinued. They put on hybid badges and used names like "Green Line" when in fact they were dirty hybrids.

They kept talking about their "leadership" in this space and created an expensive and complex two-mode system they they only it in monstrosity class (5000+ lb.) SUVs which cost $45K+ and a handful of full-sized trucks which get barely above 20 mpg which also barely sell. They go on talking about the "improvement" in city mpg over their non-hybrids. Really? People who care about good fuel economy will buy such beasts?

This past year, they put out these gems:
http://priuschat.com/forums/prius-h...-2-escalades-one-really-expensive-hybrid.html
http://priuschat.com/forums/other-cars/60248-gmc-adds-yukon-denali-hybrid-lineup.html#post897994

The Volt price estimates keep going up and up too.

The Japan-only NHW10 Prius started shipping in Japan in December 97. To this date, GM still has nothing shipping that's competitive w/the Prius. All the while, GM was busy focusing on monstrosity class SUVs and behemoths like Hummers.

Oh yes, and go look at long term reliability ratings across all GM vehicles vs. those from Toyota and Honda vs. countless statements from so many prior GM CEOs claiming their products have improved a lot and are every bit as good as imports.