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

The link is in line with most others I've seen, short on data. All it mentions is that by lowering premium octane by one will result in more actual gasoline produced. That's it, without a source.

I wonder in GM actually edited the manuals and stuff to take differing octane fuels available?

 

Fractions for premium require time and equipment at the refinery, which accounts for its higher price. There may be small amounts of changes of liquid, but these are very small.

 

Time and equipment is only part on the equation to price. There is the relative value of the various octanes in the premium gas. Toluene is a common octane booster. It is also a common base stock for other chemical processes. There is demand for the stuff in gasoline, more so in premium, beyond its use as fuel.

For fuel efficient cars, I don't think the environmental cost differences in medium(it really isn't low) and high octane fuel production will come to much difference. If it is a major criteria to a person, then they should be driving a diesel.

 

On the inside of the Ampera's fuel door there's a 95 octane label. In the EU, 95 octane is normal fuel and 98-100 octane is premium fuel.

 

I thought it displays the kWh only for each trip upon turning off the car. Does it remember the kWh consumed in previous trips (e.g: lifetime)?

I do recall that previous discussion and the monthly OnStar report. Looking at it again, the report does break down electric and gas miles. So, each Volt owner CAN calculate their own composite MPGe.

Is there a spreadsheet with data from the OnStar monthly reports to calculate the composite MPGe?

I wasn't talking about the charging rate. I was talking about the full charge time. Prius PHV would be done in 1.5 hours. Volt in 4.3 hours. Leaf in 8 hours.

We know Toyota is conservative so the charging rate is not a surprise. Volt also has a slower (12 amp) recharging setting on the standard cord and it has been recalled twice due to overheating.

We know you and Dr.I are the exceptions. The average on Voltstats.net is 36 MPG. Once the Volt run out of battery, it could be on the highway or in the city driving. I don't think you can say it'll mostly be on the highway. Per EPA, 55% of the miles are in the city and 45% on highway. It'll take 10 hours on standard charger to replenish the battery or force to use premium gas at 37 MPG (EPA).

In Prius PHV, you'll still get the class leading 50 MPG. The difference between 50 MPG and 37 MPG in a gallon of gas is 8.8 kWh. Every gallon the Volt burns, it is throwing out 8.8 kWh.

Per GM on average of all the Volts, about 40% of the actual miles are on gas (statistics predicts 42%). That's a lot of kWh not extracted from gasoline but instead pulled from the grid. Think about the amount of energy required to generate and the time it would take to recharge the battery. Per US EIA, 2/3 of the energy is loss from generating, transmitting and distributing electricity.

There are pluses and minuses for having bigger battery in a plugin hybrid. It is in my opinion that Prius PHV strikes the best balance. Volt is a great choice if you can avoid the 37 MPG gas engine. But then, you would be better off with a BEV. That is the reason why it is important to balance both EV and HV operation in a PHV. Bias toward one or another is counter productive.

 

I had some errands to run yesterday, but no electricity available. Eek!

59 MPG was the result.

Seeing that efficiency from a depleted battery is great. Good thing too. I may end up going for a loooong drive this weekend.

 

No spreadsheet of which I am aware. No need to compute it as its on the efficiency report on myvolt.com

You are comparing filling time for quarts and gallons. Tak a Prius PHV, and a Volt, Drive them in EV for say 10 miles, then recharge them. Volt will recharge faster.

I waslways find your fixation on recharge time ironic.. I recharge while I sleep.. so who cares
I don't even go for the L2 becuase I recharge while I sleep and who cares if its charging while I sleep.

The 8.8kWh is not the difference inusable energy, its the potential energy difference. But it is also irrelevant unless one factors in how often a Volt users consumes a gallon of gas compared to how often a prius user consumes a gallon of gas. Its a system and its not that meaningful to ask about the efficiency of infrequently used aspects out of context.


Every gallon of gas a Prius PHV burns going between 11 and 35 miles it is throwing away gas. Prius PHV uses are wasting more gas.
The point of overall systems efficiency is to minimize overall waste, which the larger pack allows the Volt allows more users to do. If the user's daily trips are small enough, combined with enough long trips, the PiP can do better.

Unfortunately many of your posted statement against the Volt, e.g. charge time, are wrong while other are misleading. You make many apples to banana comparisons to suite your bias.

You are welcome to your opinion of balance for your case. Just don't present it as if its better for others. The answer to what is more efficient between a PiP, Volt and a BEV depends on the family usage model and needs.

 

I believe the 2012 Volt retains the cumulative kWh along with separate EV and HV mileage counts across multiple driving segments (restarts of the car). I believe the car's display automatically resets to zero after a full battery charge much like the gen 2 Prius automatically resets the gas mpg display after a full refueling.

Others may know, but I'm not personally aware of one yet.

As of this month, GM's MyVolt.com website is again displaying detailed charging and trip segment EV vs. HV data uploaded by OnStar from the car. There is also an easy way to download that data in a spreadsheet friendly format. I haven't played with it much yet but I think you can display or download at least the last month worth of data.

A full recharge of the Volt takes between 3.5 to 4 hours.

I'm not aware of 2 recalls of the 120v charge cord. I think they improved the stress protection where the cord attaches to the EVSE box and a few people who had problems got their cords swapped under warranty. Only the more recent 120v molded plug update is an actual "customer satisfaction" service campaign and it's not technically a safety recall. Yes, the Volt's 120v charge cord support for optionally charging at the slower 8A rate is a nice feature that is rarely available on other cords.

In any case, charge rate is the only thing that really matters when it comes to "charging time".

That composite average is questionable as an indication of long-term gasoline efficiency for several reasons that could artificially bias it downward.

First, most of the cars which generated that composite result were added to Volstats.net as temperatures started getting colder in the fall of last year as sales of the Volt ramped up. All cars get worse mileage in winter temperatures. Depending on how it's climate controls are used, the Volt has the capability of boosting early heating with electricity before waste heat becomes available from the gas engine when the car is started in hybrid mode and the battery is nominally empty.

Also, in EV driving under colder temperature (26F and below), the Volt may periodically start the engine for short periods to generate waste heat. Even though this uses a relatively small amount of gasoline it will bring down mpg.

Finally, some owners registered in Voltstats.net may be using mountain mode to optimize their city mpg and in some situations this confused the EV vs. HV statistics and results in artificially low mpg numbers. GM and Volstats should work together to correct that scenario.

It obviously depends on the driving pattern of the owner. The Volt's battery range is large enough that many owners can complete an entire daily commute on battery (with or without charging at work). For these owners, the vast amount of HV driving is likely to be highway miles on longer weekend drives and road trips. Other drivers will utilize mountain mode to confine all or the large majority of their HV miles to the highway.

For these reasons, the EPA's city/highway ratio approximation  is not very useful for plugins. This is true for the PiP as well as the Volt due to it's EV/HV buttons which allow the driver to influence when gasoline is used.

People who want to avoid the alleged horrors of grid charging will not be buying plugins (or at least they won't be plugging them in if they bought for HOV access reasons....)

Of course, those efficiency concerns only apply to electricity generated by burning fossil fuels. The efficiency of generating power from hydro, nuclear, geothermal, wind, and solar is largely irrelevant.

Meanwhile, gasoline burned in even a Prius will still be wasting 2/3 of the energy present in the fuel and then there are the losses from the ~87% efficiency of refining.

Maybe that's a good theory for a Soviet-style planned economy, but a better idea is for customers to do the choosing based on their own unique needs. That requires a marketplace of cars designed with different tradeoffs.

The PiP tradeoffs are best for some people. The Volt tradeoffs are better for others.

 

USB,

Thank you for sharing the infomation, very interesting and educational read!

DBCassidy

 

I assume you know that the U.S. and Canada measure octane differently than the EU, so you can't directly compare numbers.

The EU uses RON, while over here we use the average of ROM and MON.

Tom

 

But if the driver of a small battery PHV is depending on frequent recharges in order to maximize the EV ratio of driving, charge rate is very important. It can mean the difference between getting to the next destination on EV or having to use the ICE.

During an hour long shopping trip it appears the Volt will gain more EV miles than the Prius PHV.

With the 2013 getting the Hold button, the use of Mountain mode pulsing should become less frequent, and this error's effects should have less influence, whether or not it gets fixed.

IIRC, that sub-thread stated RON in the beginning.
Fortunately, someone/s did some leg work and made us a chart for comparison.
Octane rating - Wikipedia, the free encyclopedia

 

Octane rating - Wikipedia, the free encyclopedia

There's a handy list on that page to show how things compare. The octane rating is a bit lower in the USA.

 

Voltstats.net shows 29.4% for 1000+ drivers. We have a mismatch of priors here. Either Voltstats is a poor sample of the population, or Volt drivers are more conscientious about maximizing EV in the real world than predicted.

We often cite Voltstats in our arguments, so it would be good to estimate the amount of bias in that sample. Where does GM's 42% statistic come from? Is it up to date?

 

The GM data being referred to is probably from
2012 Chevy Volt | Electric Car | Chevrolet
and it is not up to date.
Currently 61.30% EV, 38.69% ICE.

All self-reported statistics have a bias. On the positive side, voltstats is a 10% sample and since it is automatically collected data, removes lots of the self-reporting bias.

Voltstats is a self-selected group that choose to track their stats. We don't know why they all do it. Not all are focused on EV usage and minimizing ICE usage. At least a few with low EV%, have said the still use voltstats because it tracks their gas easily. Quantifying the bias is an interesting question is interesting but GM is pretty tight with the data.

Its likely some of the heavy ICE drivers simply chose not to sign up for voltstats. There are volt drivers putting on 36K miles a year..so they are burning lots of gas. There are reportedly some test-cars, which could easily be in the overall GM data, with 100K miles already. The average is a non-robust statistic so a few outliers on miles can have a larger impact.

 

The Volt, has larger battery capacity than the PIP - but at a cost in price and weight as others have mentioned on this topic. The questions I have on the Volt is - once the battery is depleted, does the Volt run strictly on the gas engine only?​

I assume the Volt has some regenering capacity to put some electrical energy back into the depleted batteries thru braking and coming to a stop. If that is the case, that is fine with me. ​

Voltstats.net (05/26/12) shows a really low 36 mpg for the fleet avg on gas mode. Why is that? ​

Also the recharge cord has a tendency to heat up? Also why only 12 amp recharge rate - that is very slow. Hopefully GM will make this right with all Volt owners. ​

For those fixated on using the Volt only in electric mode, why not buy a BEV - less money to purchase, no gas engine or tank to bother with. Also no gas to worry about!​

The PIP, or regular Prius does not "waste gas" - quite the opposite. The Prius combines the hightest efficiency of electric and gas mode combined. Toyota has perfected this thru many years of development. Even the PIP, when its battery runs down, gives the operator the choice to continue driving as is, or stop and recharge the battery off the grid. ​

Does the Volt offer this, I doubt it. For it it were true, the Voltstat.net would show higher numbers in gas mode only.​

Bottom line - GM didn't do their homework on the Volt as compared to the PIP, or regular Prius on the design concept, approach, and excution of their hybrid. GM needs to LOWER the price of the Volt in order to increase demand AND sales. Perhaps find a way to remove vehicle weight, drop the cost of battery manufacturing costs and battery weight. ​

The HSD approach is best in blending the gas energy with electrical energy. This serves as the cornerstone to hybrid design. That is why the Prius is AND will continue to be the leader. ​

To have the gas engine kick on only when the batteries are depleted in the Volt makes not sense. Why not incorporate the Atkinson / Miller design in their gas engine? Also why didn't GM use the electric motors to work the same time with the gas engine? ​

​

DBCassidy​

 

The Volt has agressive regen capabilities. And if really needed mountain mode can but charge back into the battery.

When the battery is depleted,called charge sustaining or CS mode, the volt can either generate electricity to run (series hybrid ode) or operate in a parallel hybrid mode where the volt's ICE is part of the epicyclic gears (same general concept as HSD, but with a different configuration of parts).

First, 36MPG on gas is not "really low".. its better than the real world data for say a corolla (32.4 or even the 2011 Camery Hybrid (32.6) or the Lexus HS250 hybrid 33.1


Why? Well it has a smaller engine (comparable to a GenI Prius) which is less efficient in the hybrid setup and also weights more than an Gen I prius. Second, many of the miles in a volt turn out short trips (e.g. a 45 mile trip might be 40 EV and 5 gas). Thirdly the car recommends premium but will run on regular, at reduced MPG (I know that personally) but I have no idea how much of that is in the voltstats data.

But the important this is not what is the MPG_CS, but what is the overall MPG, which on voltstats is 123.82 MPG. In comparison the Plug In Prius has an overall MPG of 70 at Fuelly. So the design traded some fuel economy in gas mode to improve the overall fuel economy.

The EVSE cord is part of a customer satisfaction item and people can exchange if desired.
The 120v volt EVSE supports both 8amp and 12amp modes. The 12 amp is the most common size for an L1 EVSE. (default L1 for IMev and Leaf are the same). It is not just the rating of the EVSE that matters, it also depends on the charger in the car. The Plug in Prius seems to draw < 1.3kw (which is 12amp at 120v), so one also needs to consider the vehicle charger.

Three reasons: range, cost, gas used. There are days I need to go well beyond the range of a Leaf. And a model S signture might work, but its 85K. And for those trips where a leaf wold not work for me if I took the CUV, I would use more gas over the year than just owning the Volt.

Not clear what you mean.. the Volt can stop and recharge off the grid just like the PiP. The Prius has more efficient hybrid mode but the Volt has a much greater electric mode, they are different points in the design space. Since electric mode driving is far more efficient in either vehicle, both default to using EV first.

Why not do HSD type blending and Atkinson cycle -- it is probably because Toyota holds a bunch of patents in that space that GM has to avoid. That an the fact that with the increased weight and small engine, its not clear it would get them the advantages many keep suggesting it would. Gen I prius was at about 41mpg with its smaller engine. Lexus HS250 does even worse than the Volt as it traded efficiency for more power/performance. Gen III Prius uses a bigger 1.8L engine so it can stay in the sweet spot more often -- but that is physically bigger and the volt was also space constrained.


Electricity is more efficient for propulsion so the goal is to maximize how often you can use it, while balancing your cost.
I think GM did is homework which is why the fleet average for the Volt has a much higher overall MPG. So the weight issue is not a major one because the overall fuel usage is down.

Back to your question of cost:

Net cost to own a Pip over a comparably equipped Prius is about 2k, for which one increases from 50 to 70 MPG (fuelly data), which is a hybrid premium of about $100 per mpg gained.

Net cost to own a Volt over a comparably equipped Prius is about 4K, for which one increases from 48 to 123MPG which is an EREV premium of about $53 per MPG gained.

And the Volt/EREV premium comes with improved horse power, torque, and quietness.

Why not spend more money making the Volt ICE more efficient? Well people are already complaining about the cost of the Volt and more custom parts = more initial cost. I would expect Volt Gen II to be better.

Different people can better use the PiP's capabilities while others can better utilize the Volt's.
Hope that answers your questions.

 

I drive mainly on electricity in my Volt but there are days and weekends when I drive farther than current BEVs go. Emergencies, plans change in middle of the day, travel to sport events, traffic detours, etc are others reason that I like the ICE/generator. One car does it all but it does electric driving more completely than other plug-ins and hybrids. It is unique in this regard.

Yes, lot of regen braking. The ICE/generator runs at WOT (not necessarily max RPM) for efficiency and may, depending, on speed produce some extra kWhs and turn the ICE off. It is a small buffer like a few % SOC. The cars stated goal is to mainly run on electricity where the cost is 1/5th.

It is 12 out of 15 amps and the max that can be pulled due to electrical codes.

 

If all you look at for GM expenses, that seems like a reasonable question. But looking at the big picture, you see heavy investment in engines anyway. Look at all the money spent on Cruze & eAssist.

It makes far more sense delivering a hybrid with a highly efficient engine that optionally offers the ability to plug in, rather than dividing resources.

That would offer the flexibility of capacity choice too. Instead, GM is stuck with a design heavily dependent on major improvements from a second generation design.

What should our expectations be?

 

Actually, they did. However, results of those studies didn't fit well with what they wanted to deliver. It's the SAAB story... ironically, GM not taking the very advice they gave them.

They knew it was a bad idea disregarding sound business strategy and went with their gut instead. After all, a powerful electric motor does indeed deliver a pleasant driving experience. But then again, so does a gas engine with lots of horsepower.

Cost comes back to haunt and middle-market vehicles aren't exciting to executives & enthusiasts.

 

Of course that is why I would buy a volt if they had 5 seats...a pleasant driving experience and quiet is golden IMO.