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Karma is too heavy for sipping fuel

The official EPA numbers came out recently for the Fisker Karma and they were much, much lower than many expected. The EPA rated the Karma at a scant 20 mpg on gasoline. Considering the car was supposed to be a green hybrid, it's rating is disappointing, especially when you think that other hybrids of the size can achieve much better numbers. The all-electric (battery) range is rated at 32 miles for a combined 56 mpg-e.
 
If you were wondering why a car with a hybrid power plant was rated so low on gasoline power, it’s due to the massive weight of the Karma. The Karma has a curb weight of 5,300 pounds. Most of the weight is due to the heavy and expensive lithium-ion battery pack that motivates the Karma in electric mode.

The Fisker Karma weighs nearly as much as an 8-passenger Ford Expedition 

With the low economy rating of the Karma and the fact that Fisker was one of the green firms that was loaned $529 million in federal funds, some are afraid it will be the next Solyndra. Solyndra is the solar firm that went under after receiving Federal funds for operation. While the EPA thinks its numbers for the Karma are accurate, Henrik Fisker thinks that drivers will see a better driving range.
 
Fisker said, "We firmly believe that most owners will get up to 50 miles of driving range on a single charge, and will use our electric-only mode most of the time they drive the car."
 
Much of the Karma is already made from aluminum, so the place to save weight is going to be the battery pack. This will be something that happens in the future as battery technology improves. Another choice would be going to lighter and more exotic materials for the construction like carbon fiber.
 
The problem is that the Karma is already priced at about $96,000 and moving to exotic materials would only drive that cost up. So far 1,300 people have placed deposits on the Karma


Fisker Karma

Source: Plugincars



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RE: Misleading Article
By autoboy on 10/25/2011 2:53:32 PM , Rating: 2
If you drive it beyond 25 miles it's not much worse than comparable vehicles. But then you look at the Porsche Panamera V6 that gets 27mpg highway and you wonder where all our money went. They are losing efficiency when operating on gas because they have an extra entropy step in converting gas energy to electric. The Chevy Volt avoids much of this on the highway because its ICE is actually connected to the drive wheels and directly powers the car at speeds above 70mph.


RE: Misleading Article
By Keeir on 10/25/2011 3:43:19 PM , Rating: 2
Sigh.

Autoboy, the 2012 Porsche Panamera V6 base gets 18/27, 21 Combined.

The Karma gets ?/?, 20 Combined. Hwy? Unknown. It might be 25, 26, or even 27.

It simply boggles my mind why people get so bogged down comparing the Karma's COMBINED number to X, Y, or Z HWY number or possible number. The Karma is NOT designed to travel 80, 90, 100 HWY Miles a day.

In comparison, even with the 27 HWY rating, a person needs to drive ~75 miles a day (max 10 City miles) to make a Panamera V6 a better enviromental choice.

The inclusion of the mechanical transmission is the worst "feature" of the Volt. It adds significant complication, mass, and creates packaging problems. All to raise a fuel consumption number than should be in use less than 10% of the time! BTW, the EPA HWY testing cycle includes very very little time spent at over 60 mph, let alone 70.


RE: Misleading Article
By autoboy on 10/25/2011 8:04:23 PM , Rating: 2
You are assuming that the Karma will get better highway mpg than city which is probably not correct considering that aggressive hybrids get better city mpg than highway because of lower speeds and efficient kinetic energy capture. Electrics motor are less efficient at high rotation speeds so who really knows what the real numbers will be. It could be 25 mpg city and 15 highway for all we know.

The mechanical transmission was designed to make the Volt a capable freeway cruiser. Without the transmission it would have had less than average highway mpg for it's class and would have been universally panned as a bad investment. A little extra weight isn't always horrible since it has little effect on steady state cruising, and the kinetic regen system on the Volt can regain some of that energy used to get the extra weight moving.

While you may live in a city, the US is a large country and freeway miles are an important part of most American's lives. The transmission kept it from being limited to a city car and turned it into a relatively efficient all around car. It made it a REAL car unlike the Leaf, which is probably a great choice for a lot of people looking for alt energy. Certainly in my home town of Palo Alto CA I see a LOT more Leafs than Volts. Still see more Tesla Roadsters though. I actually see more Model S Teslas than Volts around here but that's because I live near their headquarters.

The Model S certainly seems to me to be the real deal if you are looking for an electric car. With the 300 mile range battery it could be your primary car with no fear of range anxiety pretty much ever. It won't be your road trip car, but other than that you can have no fear of ripping around town as fast or as far as you want.


RE: Misleading Article
By Keeir on 10/26/2011 1:57:19 PM , Rating: 2
I have come to conclusion you either have insider information, or you have drank the GM Kool-Aid.

What we know from public information. The Volt, a Series Hybrid with Mechanical Connect Mode, scores 93 MPGe Combined (95/90) and 37 MPG RE (35/40). The Karma, a Series Hybrid without Mechanical Connect Mode, scores 52 MPGe Combined and 20 MPG RE. If we dive 52/93 * 37, we should get the MPG RE mode that Karma would get if using a direct connect system... 20.7... IE 21. This is within rounding errors and is essentially identical.

Why would this happen? Well, we need to look at the GM statement that the Tranmission only comes on in certain conditions above 70 mph.

If we examine the EPA testing cycles of which there are five found here http://www.epa.gov/nvfel/testing/dynamometer.htm
only one of the cycles exceeds 70 mph... the US06. It exceeds 70 mph for a total for ~30 seconds. Thus, if GM is to be believed, the mechanical connection only occures on 30 seconds of the approx 5,000 seconds that comprise completing each of the EPA testing cycles... 0.6% . Clearly this should have little to no effect on the EPA Rating!

What does this mean for the Karma? Well, it means that the Karma's HWY number likely exceeds to City and Combined number, even without the direct connection to the wheels. I believe from the information the HWY number should be no greater than 25. But this is unknowable to me. Fisker could have choosen many different ways for the ICE to react.... if Fisker choose to leave the ICE unresponsive, its possible the RE mode City is higher than the RE mode HWY. I doubt they did this however and the Karma could drain its batteries pretty fast.

A second question might be why GM decided to use such a complicated transmission if it posses such little EPA benifit... one reason could be that GM is fibbing and the mechanical connection occurs at speeds significantly lower then 60 mph (the point at which it will significantly effect EPA ratings).

But I think the answer is a little murkier. GM has also stated at no point will the ICE be the only thing pushing the Volt forward. Why even bother running the electric portion if its less efficient? Wouldn't disconnecting the electric portion be even better than? I think the answer lies in the ~111 kW electric motor and 53 kW generator. Either the motor loses torque and response at the higher speeds (requiring mechanical connection) or GM is wanting to acchieve a higher steady state output than 53 kW. Its also possible a GM engineer or manager put the mechanical transmission in simply as a fail-safe mechanism.

In any case, having examined the best case numbers, the direct connect will provide at best a 10% improvement over Series connection... and only if you truely never change the ICE RPM.

If you have insider information, good for you. But from the outside it appears GM is lying somewhat about the function and benifit of thier complicated transmisson on the Volt. Since the main benifit of the Volt is its 35 miles on electric mode, and the transmission will likely only benifit customers (GM offical version) who travel at above 70 mph more after 35 miles and then only (significantly) if they travel 30-40 miles extra at a time... not sure why everyone is being saddled to help those few customers save a few gallons of gas a year. IE, if you drive 75 miles a day (which I think is not good for a Volt, and far exceeds the average of 33 miles for Compact Sedans) the difference between 40 MPG (EPA rating with no mechanical assist) and 44 MPG (10% bonus for EPA rating with mechanical assist) the grand difference comes out to be 32 gallons a year.... over 27375 miles! Over 100,000 miles of 75 miles a day with the mechanical assist the grand fuel savings is ~120 gallons... for less than 500 dollars. Is the fancy tranmisson more or less than 500 dollars? I bet significantly more. In conclusion, I don't think the Volt's fancy transmission was a good choice (even if it works as GM claims) as an addition as the only customers that will economically benifit from the transmission are those that travel more than 75 miles above 70 mph consistantly. These customers would likely be better off with a Prius or a Diesel anyway.

I also have a problem with this

quote:
Electrics motor are less efficient at high rotation speeds so who really knows what the real numbers will be.


While true, its also important to point out that the EPA HWY Cycles take significantly more energy per mile to complete than EPA City Cycles. This concept has been masked by the incrediblely poor performance of ICE engines at low and high loads leading to lower City Mileage. Electric Engines have the same relative efficieny in comparison to ICE engines. This means in all electric modes, HWY cycles take more energy that city! But in Series mode who knows... the Volt suggests that a on the EPA HWY cycles a Series Hybrid is more efficient than a Series Hybrid on the EPA City.


RE: Misleading Article
By Dorkyman on 10/26/2011 3:22:02 PM , Rating: 2
http://www.engadget.com/2010/10/11/shocker-chevy-s...

Especially Update #4. The engineers have done an "efficiency map" and use the ICE when it makes sense.


RE: Misleading Article
By autoboy on 10/26/2011 5:27:42 PM , Rating: 2
Complicated transmission? It's a planetary gear set. It's similar to the Prius planetary gears except connected differently.

Sure they could have dropped the transmission and left off 50-100 lbs, but the claimed efficiency gains are 10-15% which is very significant considering the small weight gain.

GM pretty clearly lied about its Volt initially since they were claiming it was an electric car with extended range. All the press thought it would be driven only by the electric motors and then it turned out to be nothing more than a standard hybrid vehicle with a bigger electric motor and more battery that allowed it to operate as an electric vehicle longer than the Prius. If everyone thought it was just a better Prius, it wouldn't have gotten as much praise and you can guarantee.

The reviews of the car should be coming soon. I guess we'll see who's right.


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