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The $96,000 Fisker Karma is an exotic luxury sedan with a length of 16.5 feet, a width that surpasses 6 feet, a weight of over 2.5 tons, and it has a 403-horsepower powerplant

The U.S. Environmental Protection Agency (EPA) recently gave the Fisker Karma hybrid a lower-than-expected 52 mpg-equivalent rating in combined city and highway driving. The massive weight of the Karma was blamed for the poor EPA rating, and now, the EPA has determined that the 2012 Fisker Karma range-extended plug-in hybrid is a subcompact.

The $96,000 Fisker Karma is an exotic luxury sedan with a length of 16.5 feet and a width that surpasses 6 feet. It's weight is over 2.5 tons, and it has a 403-horsepower electric powerplant. So why did the EPA categorize it as a subcompact? The interior volume of the Karma doesn't quite make the cutoff of 100 cubic-feet that distinguishes between a compact and a subcompact.


The auto industry typically uses overall length to determine the class of a vehicle, but the EPA uses interior volume to do so. This means that the Karma cannot be compared to other hybrids such as Chevrolet's Volt range-extended plug-in hybrid because it's considered a compact vehicle. The Prius is classified as a midsize.

Fisker said the classification of the Karma wouldn’t affect sales because those willing to spend $96,000 on the car "know what they are getting." Fisker also called the EPA's fuel economy rating the "worst case scenario," and still insists that the Karma will provide 50 miles on a single charge.


Another Fisker employee was a bit more annoyed with the EPA rating and subcompact classification, saying that comparing the Karma to other subcompacts like the Chevy Sonic "gives you a good idea of how much faith you should put in these fuel economy ratings."

The 52 mpg-equivalent rated by the EPA includes 32 miles of all-electric range and 20 mpg when its gasoline engine/generator kicks in to provide electricity once the battery pack is drained.

Source: Auto Observer



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RE: efficiency + range <> efficiency
By drycrust3 on 10/28/2011 8:57:20 PM , Rating: 2
Hello ... I hate to disappoint you, but I do think, which is why I think that figure is nonsense! The text clearly states the 52 mpge rating is obtained by adding the 32 miles range of the batteries with the 20 mpg fuel efficiency rating. Thus, there is no indication of the efficiency of rectifiers, the batteries, and the electric motor in this rating. You could have used thermionic diode rectifiers and lead acid batteries and still got the same result, but the cost in your monthly power account would have been very different. There is no indication to the end user as to how much energy is used when driving, so the user has no idea what it will cost to travel. While I accept there is a need to present fuel efficiency figures in terms we can all understand, the current rating system is just playing with numbers to please hybrid car sales people.
I calculated the MPGe would be about 21.8 MPG over a distance of 230 miles, which is the maximum range of the vehicle using petrol and electricity. 14% of that distance was considered to be powered by electricity and the other 86% by petrol.
To me, the only fair way to take into account the different fuel injection techniques, the different battery sizes, and the other 101 other differences between one make and model and another make and model of hybrid is to base the efficiency rating on the maximum distance it can travel, then relate the electrical efficiency to the distance to it contributed, and the petrol efficiency to the distance it contributed.
The current system has an "efficiency" rating based upon an indeterminate distance and varies from driver to driver, thus it cannot be used to compare one car with another.


RE: efficiency + range <> efficiency
By Keeir on 10/30/2011 12:29:51 AM , Rating: 2
You certainly don't sound like you thought things through. I recommend for one thing not trusting Kaiser and reading at least one of the other 3 articles on the Karma here or go straight to the EPA label.

In your method of calculation, all the Karma would need to do to raise its efficiency rating is to reduce the size of the gas tank... or increase the size of the battery. Maximum Range has very little to do with efficiency.

We can both agree that Efficiency should be measured as X Consumed/ Y Miles or Y Miles/ X Consumed

But what should Y miles be? Clearly it should be consistent from car to car. It should also be a number relevant to the consumer. For example, the average car trip in the US is ~18 miles long from start to finish. Maybe that's a good point to start? No... in that case the consumer would have many unanswered questions as several plug-ins would get huge scores.

SAE developed using 2001 US Driver Data a profile of the Average US driver that tableted over a year the number of 10 mile, 20 mile, 30 mile, etc, etc driving days. They then created a curve to relate Electric Range and Electric Utilization for the Average US Driver in 2001. IE, for the Karma the Average US Driver in 2001 would use electricity 60% of the time! Even better this system accounted for mixed mode driving by allowing any two sets of propulsion to be mixed... even if there are not discrete.

In this SAE Method, efficiency is shown as a sample of 100 miles of the average efficiency over the entire year.

I still think this is a good place to start. For the average US driver of 2001, the Karma has an overall efficiency of ~31 MPGe.

Your method means next to nothing. Hopefully the average consumer would not wait till their fuel ran out to charge the battery. Most people do not drive 230 miles a day after all.


RE: efficiency + range <> efficiency
By drycrust3 on 10/31/2011 6:59:28 AM , Rating: 2
quote:
Maximum Range has very little to do with efficiency.

Well, if maximum range has little to do with efficiency then why is the MPGe rating obtained by adding the electrical range to an actual efficiency rating (MPG)?


RE: efficiency + range <> efficiency
By Keeir on 10/31/2011 2:29:24 PM , Rating: 2
Read the EPA sticker.

Go to Google.com

Search Fisker Karma EPA Sticker

Carefully look at the sticker, at let me know what you think the sticker says... its pretty clear to me.

The Karma gets 52 MPGe in Electric Mode and 20 MPG in Gasoline Mode


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