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This weekend I'll be renting a Chevy Volt for my trip to Boston from NYC (recall that I keep my Karma in LA). I'll have it for three days, so I'm excited to compare its powertrain to the Karma's. I'll post my thoughts when I'm back. Stay tuned!

Also, any other Karma owners on this forum also have a Volt? Would love to hear your thoughts and comments.

EDIT: Moderators, please move thread to the Car Lounge. Thanks!
 

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SoCalGuy said:
This weekend I'll be renting a Chevy Volt for my trip to Boston from NYC (recall that I keep my Karma in LA). I'll have it for three days, so I'm excited to compare its powertrain to the Karma's. I'll post my thoughts when I'm back. Stay tuned!

Also, any other Karma owners on this forum also have a Volt? Would love to hear your thoughts and comments.

EDIT: Moderators, please move thread to the Car Lounge. Thanks!
We have a Volt. It's my wife's daily driver with roughly 16K miles on it. I driven it enough to speak about it. The power train, while not as powerful as the Karma, works very well. When the ICE kicks in it is noticeable from a noise perspective, just as the Karma's is. It does have a sport mode which gives it a little more pep.

I'm interested in your take on the Volt command center. I find it to be more responsive than the Karma, but the plethora of buttons are hard to deal with.
I like the Karma's layout better, but wish it had the responsiveness of the Volt's.
 

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Discussion Starter · #3 ·
ejo3rd said:
SoCalGuy said:
This weekend I'll be renting a Chevy Volt for my trip to Boston from NYC (recall that I keep my Karma in LA). I'll have it for three days, so I'm excited to compare its powertrain to the Karma's. I'll post my thoughts when I'm back. Stay tuned!

Also, any other Karma owners on this forum also have a Volt? Would love to hear your thoughts and comments.

EDIT: Moderators, please move thread to the Car Lounge. Thanks!
We have a Volt. It's my wife's daily driver with roughly 16K miles on it. I driven it enough to speak about it. The power train, while not as powerful as the Karma, works very well. When the ICE kicks in it is noticeable from a noise perspective, just as the Karma's is. It does have a sport mode which gives it a little more pep.

I'm interested in your take on the Volt command center. I find it to be more responsive than the Karma, but the plethora of buttons are hard to deal with.
I like the Karma's layout better, but wish it had the responsiveness of the Volt's.
Thanks for the insight. Looking forward to my trip this weekend. Will let you know my experience!
 

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Discussion Starter · #4 ·
235 miles and counting. I have to say, the Volt is pretty awesome. The transmission from pure electric to the range extend mode is seamless. Engine is much quieter than the Karma, and it appears to charge the battery enough so that you get a a fair amount of range in between range extend generations (e.g. engine turns on for a bit, then shuts off, but I'm still able to cruise around 20-30mph for a good mile or two before the engine kicks in again)...and the Navigation is great. Easy to read screens, super easy to input Destination mode, and audio levels/voice notifications that are clear and succint (and timely!). If she looked better, I'd have gotten her =)

Also, I noticed up around 75-80mph, when you floor the accelerator, there is definitely a lag before incremental juice is given, and even then, acceleration from say 75 to 85mph is sluggish.
 

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SoCalGuy said:
235 miles and counting. I have to say, the Volt is pretty awesome. The transmission from pure electric to the range extend mode is seamless. Engine is much quieter than the Karma, and it appears to charge the battery enough so that you get a a fair amount of range in between range extend generations (e.g. engine turns on for a bit, then shuts off, but I'm still able to cruise around 20-30mph for a good mile or two before the engine kicks in again)...and the Navigation is great. Easy to read screens, super easy to input Destination mode, and audio levels/voice notifications that are clear and succint (and timely!). If she looked better, I'd have gotten her =)

Also, I noticed up around 75-80mph, when you floor the accelerator, there is definitely a lag before incremental juice is given, and even then, acceleration from say 75 to 85mph is sluggish.
My wife and I also like the Volt. It definitely has a lot going for it. A little more power would have been nice though. Keeping a little more of the concept looks also would have helped. I don't know if the rental has OnStar, but that takes the nav system to another level. Just push the button, tell them where you want to go and its downloaded to the system. Pretty slick. And it's included for five years when you buy the car.
 

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Discussion Starter · #6 ·
ejo3rd said:
SoCalGuy said:
235 miles and counting. I have to say, the Volt is pretty awesome. The transmission from pure electric to the range extend mode is seamless. Engine is much quieter than the Karma, and it appears to charge the battery enough so that you get a a fair amount of range in between range extend generations (e.g. engine turns on for a bit, then shuts off, but I'm still able to cruise around 20-30mph for a good mile or two before the engine kicks in again)...and the Navigation is great. Easy to read screens, super easy to input Destination mode, and audio levels/voice notifications that are clear and succint (and timely!). If she looked better, I'd have gotten her =)

Also, I noticed up around 75-80mph, when you floor the accelerator, there is definitely a lag before incremental juice is given, and even then, acceleration from say 75 to 85mph is sluggish.
My wife and I also like the Volt. It definitely has a lot going for it. A little more power would have been nice though. Keeping a little more of the concept looks also would have helped. I don't know if the rental has OnStar, but that takes the nav system to another level. Just push the button, tell them where you want to go and its downloaded to the system. Pretty slick. And it's included for five years when you buy the car.
It's got the OnStar button but I haven't tried it yet. The execution on the drivetrain is amazing - very smooth/seamless. Fisker, have you heard of the Volt? Check it out. What I'm also surprised by is that the Volt only ways 3750lbs, while my Karma weighs 5300lbs. Granted we've got more hp than the Volt, but I wonder why FIsker couldn't have achieved the same weight class =/-200lbs with a larger electric motor. Or conversely, why the Volt didn't have the skin of the Karma. I know cd had something to do with it - the Volt I think is 0.28 and the Karma is 0.31 (seemingly small difference, but that translates into 12% more drag, and thus roughly 6-8% less fuel efficiency for a given weight).

I'm also loving the capacitive touch buttons for A/C control and radio... no need to fuss with the touch screen to increase fan speed or turn it off, change radio stations, etc. Pretty well thought out. And man oh man, I love the input screen for the Nav system - super easy to use.
 

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SoCalGuy said:
I have to say, the Volt is pretty awesome. The transmission from pure electric to the range extend mode is seamless. Engine is much quieter than the Karma, and it appears to charge the battery enough so that you get a a fair amount of range in between range extend generations (e.g. engine turns on for a bit, then shuts off, but I'm still able to cruise around 20-30mph for a good mile or two before the engine kicks in again)
GM spent _a lot_ of time on NVH engineering and the ICE generator profile. Particularly the algorithm that maps the accelerator pedal position to engine RPM. Many months were spent essentially tweaking software to find the right balance between efficiency and driver comfort/expectations.
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SoCalGuy said:
The execution on the drivetrain is amazing - very smooth/seamless. Fisker, have you heard of the Volt? Check it out.
I kinda got ridiculed when I made that comparison in the past, based solely from an engineering perspective.

You should read this thread: http://fiskerbuzz.com/forums/Thread-Cadillac-confirms-plans-for-PHEV-coupe-named-ELR
 

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SoCalGuy said:
... What I'm also surprised by is that the Volt only ways 3750lbs, while my Karma weighs 5300lbs.
Biggest chunk of reason-for-that is that the Karma uses a space-frame (which is what you get when you're making 10k vehicles per year) instead of monocoque construction (which is what you do when you're making 150k+ vehicles per year). The Volt re-uses the Cruze body so even if the Volt "only" sells 20k vehicles in a year, the cost of the fancy light-weight the-shell-IS-the-"frame" construction pays off.
 

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Discussion Starter · #9 ·
ct-fiskerbuzz said:
SoCalGuy said:
... What I'm also surprised by is that the Volt only ways 3750lbs, while my Karma weighs 5300lbs.
Biggest chunk of reason-for-that is that the Karma uses a space-frame (which is what you get when you're making 10k vehicles per year) instead of monocoque construction (which is what you do when you're making 150k+ vehicles per year). The Volt re-uses the Cruze body so even if the Volt "only" sells 20k vehicles in a year, the cost of the fancy light-weight the-shell-IS-the-"frame" construction pays off.
Intriguing. Order of magnitude, how much does one weigh versus the other (eg 500 lbs vs 1400lbs)? Any idea what Tesla us doing? Don't McLaren and Ferrari use monocoque (I know they are higher price points and use carbon fiber too)?
 

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SoCalGuy said:
ct-fiskerbuzz said:
SoCalGuy said:
... What I'm also surprised by is that the Volt only ways 3750lbs, while my Karma weighs 5300lbs.
Biggest chunk of reason-for-that is that the Karma uses a space-frame (which is what you get when you're making 10k vehicles per year) instead of monocoque construction (which is what you do when you're making 150k+ vehicles per year). The Volt re-uses the Cruze body so even if the Volt "only" sells 20k vehicles in a year, the cost of the fancy light-weight the-shell-IS-the-"frame" construction pays off.
Intriguing. Order of magnitude, how much does one weigh versus the other (eg 500 lbs vs 1400lbs)? Any idea what Tesla is doing? Don't McLaren and Ferrari use monocoque (I know they are higher price points and use carbon fiber too)?
I can't find any hard numbers on this.

In theory, a space frame could actually be lighter. However, there are a bunch of tradeoffs you have to make, between stiffness (space frames are very good for this), construct-ability, and safety. Monocoque construction gives you great safety-at-light-weight through the magic of having the car crumple up like a ball of foil in a crash. (The car is a total write-off after that, but the passenger compartment, and most important, the passengers themselves, take very little of the destruction.) To get safety with space-frame construction, they generally add some weighty bits that absorb sudden delta-Vs.

Materials matter too: carbon fiber is tremendously strong and light, but also terribly expensive. Monocoques are usually (very) thin sheet steel, which is easy to manipulate and weld, while the Karma uses aluminum for its space frame, which is strong and light but harder to work with.

There's no physics-level fundamental reason for carbon fiber to be so expensive, and Amory Lovins (at the Rocky Mountain Institute) is trying to come up with processes that will be cheap enough for mass production. No great luck so far though.
 

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ct-fiskerbuzz said:
There's no physics-level fundamental reason for carbon fiber to be so expensive, and Amory Lovins (at the Rocky Mountain Institute) is trying to come up with processes that will be cheap enough for mass production. No great luck so far though.
When McLaren made the F1 road car in the mid 90's, the carbon fiber tub required 4000 hours of labor, which helped account for its $1M price point. Through innovation and automation, the carbon fiber tub in the 2012 MP4-12C requires just 4 hours of labor. While $230K MSRP is still expensive, McLaren has reduced the entry point for a carbon fiber chassis down from $375K (Porsche Carrera GT, McLaren Mercedes SLR, Lexus LF-A).
 
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