Volt to get 100 mpg certification?

[Dr Mordrid]

Bloomberg.....

The bottom line is that GM is very close to getting a 100 mpg certification from CARB (the California Air Resources Board), a cert that will go a long ways towards getting a 100 mpg rating from the EPA (Environmental Protection Agency).

If this comes to pass the Volt will be the first car to achieve a 100 mpg ranking. It remains to be seen if this will also qualify it for the Progressive Automotive X-Prize.

[Kruzin]

These ratings are never even close to realistic.
Cars rated at 40mpg are lucky to get 25-30.
While Volt may get good mileage, in real world use it will never see 100mpg.

[Helevitia]

They revised the MPG ratings for 2008 and up, so they are much more accurate, though I don't know how much.

I think the prius dropped 12mpg from 2007 to the new 2008 ratings.

[Brian Ellis]

How can an electic car get any mpg rating? The same goes for plug-in hybrids. The only valid way the Volt could get an mpg rating is if starts the test with a flat battery. Carbon emissions with fossil-fuel fired electricity are always higher with electric cars than an equivalent fossil fuel car.

As for the EPA ratings, check out http://www.cypenv.info/hybrid/index.htm and especially the 13 December update in the My first thoughts, after the EPA. There you will find that the 2007 ratings for my 2007 car are pretty accurate. You can also check out, under the EPA page, what other users obtain and the average is pretty much what the EPA says, maybe even a little better.

[Dr Mordrid]

How can an electic car get any mpg rating? The same goes for plug-in hybrids.

There is a new rating called MPGe (Miles Per Gallon gasoline Equivalent). It assigns a GGE (Gasoline Gallon Equivalence) to alternative fuels, including electricity, which can then be used to calculate the MPGe.

PHEV's like the Volt use both electricity and a liquid fuel, but not necessarily gasoline. In the first Volts case this could be either gasoline or E85, but a diesel/biodiesel version is also in the works. Here’s the basic formula:

MPGe = EG / (g*EF + e*EW)

where

m = miles per gallon of liquid fuel used (MPG)

g = 1/m = gallons of liquid fuel used per mile (GPM)

e = plug-to-wheels electrical energy used per mile (Wh/mle)

EF = BTU per gallon of liquid fuel used (not necessarily gasoline)

EG = BTU per gallon of gasoline = 116,090

EW = BTU per Watt-hour (Wh) of electricity = 3.412

(formula: Progressive Automotive X-Prize)

[Brian Ellis]

Your side of the Atlantic, it is called the fudge factor. Our side, the fiddle factor. That equation is totally meaningless because it does not take into account the fuel used to generate the electricity. In terms of carbon emissions, which is the name of the game, the raison d'être, of fuel-economy cars, I maintain that electric or plug-in hybrids, are worse than straight hybrids.

In other words, it does not take into account the Well-to wheels efficiency:

Depending on the vehicle, the figure varies due to differences in energy extraction and transfer. For instance a vehicle with a SI (Spark Ingition) engine that used gasoline, would, according to the DOE[1], use a factor of .83 for petroleum refining and distribution efficiency, in addition to it's EPA fuel mileage rating.

On the other hand an electric vehicle, powered by a mix of electricity generation methods, would use a weighted sum of the energy needed to acquire the energy received from the various sources, as well as it's charging/discharging efficiency, drive-train efficiency, and energy required to move it per unit distance.
Effect of Well-to-Wheel Analyses

The following table gives an approximation of the efficiencies and indices for carbon emissions and other pollution for various types of cars. It must be considered that these may vary a lot, according to local conditions, so the figures are purely indicative. The table is followed by some explicative notes.
Type of car W>W efficiency
estimate, per cent W>W carbon
index Pollution
index
Petrol-electric hybrid 20 1 1
Small efficient diesel 20 1.0 1.2
Conventional petrol or diesel 16 2.0 2.0
Plug-in hybrid Nuclear/renewable 18 0.9 1.2
Fossil fuel 2.5 2.5
Electric Nuclear/renewable 14 0.8 1.0
Fossil fuel 3.0 3.0
Fuel cell Reformed CH4 <10 2.5 2.0
Nuc/ren electrolysis 0.8 1.0
Fossil electrolysis 3.0 4.0

Notes:

1. The reference car is a mid-sized hybrid car, such as a Toyota Prius or a Honda Civic Hybrid. Cars of different sizes have to be pro-rataed to equal these in performance, size and weight.

2. The figures are approximations, based on what are considered average conditions, with modern commercial cars, in developed countries, most of which have to import or transport their energy over considerable distances. With cars that are not yet commercially available, the figures are assumed from available data and engineering practice. Special "concept" and small series cars are not considered.

3. The indices refer to the reference car.

4. The "small efficient diesel" refers to European marques, such as Volkswagen or Peugeot, fitted with particle filters. They definitely pollute more than the reference vehicles a) because the particle filters are inefficient with ultrafine particles and b) because of other pollutants due to less refined fuels and different combustion conditions, notably nitrogen oxides, sulfur dioxide and hydrocarbons.

5. Nuclear/renewable electricity is never totally carbon-free or pollution-free.

6. Electric cars and plug-in hybrid cars when running on electricity charged from power grids have very poor overall efficiencies because the average power station has an efficiency even lower than the modern internal combustion engine.

7. Fuel cell cars are assumed to use hydrogen.

8. Most hydrogen is made from reforming methane from natural gas, a process that emits carbon dioxide and many other air pollutants.

9. No attempt has been made to indicate relative costs because of different conditions, such as fuel taxation, distribution and electricity costs etc., from country-to-country and even within countries.

Because the table is garbled, I screen-captured it:

[IM_Riktar]

These ratings are never even close to realistic.
Cars rated at 40mpg are lucky to get 25-30.

Not always. The SX4 my wife drives is rated at 24 city, 30 hwy. The only time we see mpg close to 24 (25-26) is in the winter. During the spring/summer/fall we are pretty much hanging at 29mpg.
We do live in a rural area that is mostly county trunk roads and highways with speed limits of 55mph.
On the only long distance trip (850 miles one way) we were a bit disappointed with only 28mpg but since the car had barely 8000 miles on it's ticker I will chalk that up to the motor not being broken in. Of course keeping the speed at 75 with the AC blasting didn't help.

[Dr Mordrid]

Our Dodge Caravan's also routinely exceed their sticker mileage estimates.