Comments on: Confusion Over MPG Ratings for Electric Cars

By: Richard1

Richard1 — Sun, 07 Aug 2011 17:13:54 +0000

I was wondering if the EPA looked at the BTU's required to generate the KWH that are used to charge the batteries in the electric vehicles?

When you take into account the power plant efficiency, transmission line losses, the efficiency of the battery chargers the numbers don't look as good.

The Volt on its batteries run in the 15 to 20 mpg range and the Leaf run in the 25 to 30 range whwn looking at the BTUs needed to generate the KWH.

By: David Raikow

David Raikow — Thu, 13 Aug 2009 18:48:03 +0000

If it consumes fuel at all, show us the curve:

http://rivercontinua.wordpress.com/2009/08/12/gm-volts-230-mpg-requires-new-ways-of-thinking-about-gas-mileage/

By: Macz

Macz — Wed, 12 Aug 2009 22:44:20 +0000

I'm with redbeard and picky,
Keep this simple. All anybody really wants to know is how far can I get before the car needs re-fueling, regardless of the fuel.
Why so complicated?

By: Perspective

Perspective — Wed, 12 Aug 2009 14:51:43 +0000

Since, at vehicle level energy use, an internal combustion engine (ICE) runs at around 25% efficiency, real world, and an electric motor runs close to 100% efficiency, most folks will be very hard pressed to believe that a vehicle that uses both, such as the Volt, could in any way be rated as more efficient (230 mpge) than a vehicle that uses only a more efficient electric motor, such as the Mini-e (33 kWh / 100 miles ~ 102 mpge).

Someone has some 'splainin to do. It's just not credible that anything with an ICE as part of its energy use could be more efficient than an all electric, at the vehicle level, which is the level EPA has always reported.

hint: If you are going to add in original energy source, electric transmission, distribution or market costs for electricity for electric vehicles, you also have to add in all military, transportation, distribution and other crude oil costs since the start of the last century for vehicles that use gas to be fair.

By: EVO

EVO — Wed, 12 Aug 2009 14:40:16 +0000

kilowatt hours per 100 miles IS, IN FACT, already the EPA/DOE official measure for electric drive vehicles.

An example is the official EPA efficiency sticker on a new mini-E.

MPG is a meaningless metric for anything with 100% electric drive. It's at vehicle energy use efficiency that the EPA tries to report, and kWh / 100 miles gives it to you for electric drive.

The smaller the number of kWh / 100 miles the vehicle uses, the more efficient the vehicle is. Simple.

By: Priusmaniac

Priusmaniac — Thu, 06 Aug 2009 15:16:17 +0000

It looks rather simple for pure EV vehicles; miles per KWh is quiet convenient because it gives a value like 5 or 6. Otherwise, for a plug-in hybrid, I would use miles per KWh in EV mode and mpg for the hybrid mode. Although in the hybrid mode, there is also interest in the KWh/gallon value, which measures the efficiency of the onboard electricity generator. This can start at 10 KWh/Gallon and go up to 20 KWh/Gallon or more.

A completely different way of looking at it is fossil CO2/mile. Which can be zero for both EV mode and pure non-fossil fuel hybrid mode. For example using E100 or B100. Although the entire chain without fossil CO2 is difficult. In the case of the EV mode, producing the steel for the pylons transporting the electricity and the copper for the wires still represent some fossil CO2. The same can be said for the E100 because of fertilizers and transport, although bio agriculture combined with E100 powered process and transport can be an answer to that.

By: Jon

Jon — Sun, 02 Aug 2009 05:37:21 +0000

Wow… you’ve been drinking that ethanol cool-aid haven’t you!

Perhaps they could factor in all the petro based fertilizers that go into Ehtanol too oh and the federal tax dollar subsidies…. and they could reduce the efficiency for Ethonal’s lower power content…

Seriously, do you really need even more complicated labels to help your buying decisions? Couldn’t one just do the consumer research themselves?

By: Libor

Libor — Sat, 01 Aug 2009 13:36:52 +0000

Pickey,
1) The "5th graders" will be able to compare apples with apples. Trust them. The more energy it uses, the worse it is. 60 is more than 30, 30 is more efficient.
2) You really need a solid, un-debatable scale for efficiency - i.e. government agencies need rock solid data for their decisions, journalists need it for good reviews, and I belive that most of the people want to have true data.
Don't forget, that even in case of most complicated scale you can ever imagine, there will be plenty of marketing rubbish written on leafelts, advertisements, etc. Reviews will be written, experience shared.
So a big YES for Kwhr/100km or similar unit.

By: sean t

sean t — Fri, 31 Jul 2009 04:07:26 +0000

Pickey,
They may be a 5th grader but not totally un-educated.
If the current unit is MPG or l/100km elsewhere then what is wrong with KwH/100Km or KwH/Km? Or Mile per KwH?

By: Pickey McPickey

Pickey McPickey — Thu, 30 Jul 2009 18:01:10 +0000

Marketing Rule #1
We need to speak to people as if they had a 5th grade education:
Most consumers want to know only 3 things:

How long can I drive it before I have to re-charge?

How long will it take to Fully Recharge? (110 & 220)

How much (on average) will it cost me to recharge based on average electricity costs and driving miles of 12,000 miles per year?