calculation details of Volt's 230mpg city estimate

just remember the car is at 65% in terms of programing, the whole SOC system is "unstable" right now and not tuned, kinda like driving around with no oxygen sensors and a clogged air filter

 

Sure, whatever. Wake me up when the 'programming' improves the car's CS fuel economy to 50+ mpg.

btw, take this for what you will,

said the chief of Volt powertrain dev this week. I read it as just another step in GM's long road of deflating expectations after all the hype. I'm just waiting for the entertainment when GM goes about explaining how 40 EV miles is 25 EV miles when driven by ordinary people on their daily routes.

How about a Hype Deflator Counter ?
Initial cost hype: $25k
Initial CS mpg hype: 50 mpg
Initial EV range hype: 40 EV miles

I think the car will end up as 25 EV, 35 - 40 CS mpg, $45 - 50k. I'm happy to be wrong. Please don't spin the cost because of tax credits. First off, the credits will not be around for long, and second, AMT will take care to wipe them out for many.

 

Good point FX.
However, I am skeptical of GM's ability to deliver. Very hopeful, but skeptical.
I will be one of the first in line to test drive one of their Volt's, but they will have to show me the goods before I believe they can actually deliver.

 

32 MPG is very low when Cruze is expected to get highway 40 MPG.

 

usbseawolf,
I've been meaning to clarify the 32 mpg. The author wrote something along the lines of distance/gallons was 38 mpg. I corrected for 40 EV miles, but after I posted I realized that the battery may not have been totally charged, and certainly did not have to last 40 miles. So less than 38, and perhaps more than 32 mpg is a more accurate statement.

 

Link please? I did a search with Google and turned up no articles mentioning anything NEW on Volt MPG other then one that had 200mpg on the display (meaning nothing with no context).

Today Show Presents First Review of Chevy Volt in Charge Sustaining Mode - All Cars Electric

 

Hampdenwireless,
I think the review I read was from Edmunds, but I cannot find it. However on the Edmunds site I found this blog entry from the Edmunds staff, that appears to reference the same data I originally quoted. The relevant part is

I calculated 32 mpg as (230-40)/6

 

This is false. You're repeating it only to try to keep your visions of the 90's intact. In fact there are only two full sized vehicles in the top 10 and both are dropping like rocks in the rankings. The F150 and the Silverado are the only full sized holdovers from the 90s.

The growth is in midsized autos, compact cars, hybrids and small crossovers. Those are the facts any other statement is pure dreamspeak. C'mon it's OK to join the 21st Century.

 

In regards to comparing the Metro's and the diesel Chevette there are at least three points that you ignore why no person in their sound mind would buy either of those pigs today.

1. Neither had any safety features other than two airbags and seatbelts. No buyer would give them a second look.
2. The Metro couldn't beat a donkey cart in a race much less the Prius.
3. The diesel Chevette is unsellable in all 50 states.

WAKE UP!!!! We're 10 yrs past the 90s.

 

In fairness the Volt will have a liquid fuel economy rating somewhere between infinity and 35-40 mpg. We just don't know yet.

When the vehicle is in Charge Sustaining mode after battery depletion we just don't know how much and how often that engine will run to charge the battery. It allegedly will have an 8 gallon tank.

The 1.4L engine I believe will be tuned to the Atkinson cycle also ( Miller cycle if it's a turbo engine ). The vehicle is the size of a Corolla or Scion tC, but it has a lot more weight due to the battery. Since the ICE won't be driving the wheels it can run efficiently but I just don't have any data to guage how long it will go before the 8 gal tank is drained.

If a driver doesn't go farther than 40 mi per day then the vehicle could go almost indefinitely on electricity.
If a driver decides to drive to California from NYC and back without recharging then it's 6000 mi / x gallons

 

Your numbers do what the EPA did - assume the price of the charge is FREE. Right now, I pay as much for 16 kilowatt-hours as I do for a gallon of gas - how hard is it to factor that in?

The Volt's battery will take 8.8kWh per charge. Assuming the charger is 90% efficient, a full charge costs about as much as 0.6 gallons of gas. Assuming you drive it gently enough to get a full 40 miles out of that charge, then you're getting 65MPG. You can massage those numbers a bit if you want, but you can not get above 100MPG without a lot of fudge. Then the less-than-50mpg gas engine kicks in, and you don't have the same power.

Electrics like the Volt or Leaf have a place, and that place is low-distance, low-/moderate-speed - if that's the kind of driving you do a lot of, then you can do 27% better than the Prius. (probably quite a bit more in non-tropical climates where the Prius needs longer distances to warm up and reach max efficiency)

 

How much do you pay for electricity?!? the nation average for a gallon of gas is $2.35. that would be .16 per kwh. That's more expensive than san francisco and new york city! if you are paying that much for electricity it would bode well for you to invest in photovoltaic panels or wind turbines. Your electric bill for your one house is that of both of my properties.

Battery chemistry is only going to improve so at this stage it might not be the clear financial winner (neither is the prius over an ICE). the data this guy used is on a plug in prius which HAS to turn the ICE on over a certain MPH. That is nothing like a Volt or a Leaf.

Leaf 100 miles 24kwh battery capacity. so that would cost 24x.16=3.84

Volt 100 miles 16kwh (40 mile EV) (40x.16)+(1.5x2.35)=6.09
(assuming the volt gets 40mpg)

Prius 100miles 2x2.35=4.70

it's clear that the volt is the costlier to drive over longer distances and the Leaf the cheapest.

 

I don't know about Tom but we are currently paying $0.147267/kWh. I last filled up the car at $2.679 so 8.8kWh charged at 90% would currently cost 53.75% of a gallon.

Most Mainers live in the south of the state and it's bad for solar. Northern Maine is just average for solar.

 

I also did a spreadsheet calculations and for the electricity cost I was a bit less generous and assumed the stated 8 hours * I was a bit less generous than you. But following your energy*ppu/efficiency calculation gives me an estimated charge cost of 8.8*$0.147267/0.9 = $1.4399. Last fill-up was at $2.679 so I get 53.7% of a gallon.

Anyway, I estimated our driving patterns and guessed at the amount of charging we would be able to do at 110V when at friends and family (and including that as a cost, what kind of person do you think I am? ) then assuming:
- A Volt would given 38mpg in HEV mode
- A Prius would give 50mpg
- Total miles per year 17,703.2

	Column 1	Column 2	Column 3	Column 4	Column 5	Column 6	Column 7	Column 8	Column 9	Column 10	Column 11	Column 12	Column 13
0	$/gal	$/kWh	Car	40AER	36AER	32AER
1	2.679	~.147	Volt	62.57	+$190.50	55.40	+$92.41	49.67	-$6.35
2	4.000	~.157	Volt	77.44	+$501.83	66.82	+$356.51	58.73	+$210.48
3	2.679	~.147	Better	13	[email protected]	+$212.54	13	[email protected]	+$124.42		12	[email protected]	+$36.77
4	4.000	~.157	Better	16	[email protected]	+$514.60	13	[email protected]	+$382.68	13	[email protected]	+$251.52

Better=Drive better of Prius or Volt
[##,###.#@]##.## = [Number of (PH)EV miles at] equivalent mileage by gasoline cost.
+/-$ = Annual + saving - loss in dollars compared to a Prius.

And just for fun, here's the Leaf, assuming 16kWh of energy needed for the "full" charge. (Only "Better car" comparison since we'd have to have two)

	Column 1	Column 2	Column 3	Column 4	Column 5	Column 6	Column 7	Column 8	Column 9	Column 10	Column 11	Column 12	Column 13
0	$/gal	$/kWh	Car	100AER	90AER	80AER
1	2.679	~.147	Better	13	[email protected]	+$370.39	13	[email protected]	+$331.06		13	[email protected]	+281.91
2	4.000	~.157	Better	13	[email protected]	+$703.51	13	[email protected]	+$661.51	13	[email protected]	+$609.02

As you can see, for us the Leaf could win just on fuel costs if gas prices were high. That's because we have many 40-50 mile round trips that would allow us to make good use of the capacity.

 

I still say that any attempt to give a combined MPG number for a PHEV is dishonest, and when that number pretends that electricity is free, it's criminally dishonest. (No surprise that GM does just that!)

GM needs to tell us (or the EPA needs to require them to run the tests and publish the numbers) how many miles per gallon it goes when the gasoline engine is running, and how many Wh it uses per mile (or how many miles per kWh) when in electric mode. Then they also need to tell us how much electricity the heater and air conditioner draw at full blast. We can then run numbers for particular distance commutes, and factor in small, medium, and large heater and A/C demands.

Why won't they give us clear numbers? Because they are trying to scam us, that's why.

 

To give GM a fair shake, there really isn't a set way to measure this BY REGULATIONS. Heck, the EPA gave the Roadster a mpg number!
The EPA requires a MPG reading and has been slow to adopt a better measure.
Right now, I think the quickest way to implement this would by a set of mpg estimates.
One for if you drive 20 miles, then 40 then 60 then 100 or something of that sort.
The general populace also has to be able to take at least a little effort in understanding these things.
I am still amazed by how many people assume they will always get the exact mpg number in any type of conditions or driving behavior.