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Automotive News & Views GM News, New Models and Market Share
8042 messages, Last post on Nov 07, 2009 at 8:32 PM
You are in the Automotive News & Views Forum. Your Hosts are steve_ & claires
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"General Motors has reaped a ton of publicity from its Chevrolet Volt, a car with a grid-charged battery pack that will power an electric motor and an on-board gasoline engine that will generate electricity to keep the electric motor running and recharge the batteries when the initial plug-in charge is depleted. " http://www.edmunds.com/insideline/do/News/articleId=132112
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Replying to: toyota4life (Sep 23, 2008 5:09 pm) I just copied and pasted that BUT it does make more sense to directly run the electric motor from the gas engine once the battery is down to 30%. It is inefficient to charge the battery from one power source and then use that battery to run the vehicle. The battery is still charged from regenerative sources (braking). Most likely it is still a BAS system and the engine shuts down at stops. Also why charge the battery from the gas engine when you may not need the battery power. Better off to wait til you get to a cheaper power source (home). It does charge the battery once it gets below 30% (minimum desired charge level). The on board electric components get their power from the battery and you would hate to have the brake lights or A/C stopped working if the battery got too low. All makes sense.
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Replying to: 62vetteefp (Sep 24, 2008 3:16 am) >And by "sustaining" GM says that it means only that no additional power is drained from the batteries. Get it? The tone of Mr. Pund's article sounds like he's trying to make it negative that the Volt has batteries! His statement says the engine does not recharge the batteries, but indeed the batteries are being recharge to maintain the 30% level. Perhaps some engineering school for Mr. Pund? I suspect Mr. Pund would have loved the logical system were the name on the badge Toyota or Honda. |
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Wonder how they figured the 70%? There's something in the package for consumers, too: up to $7,500 to buy plug-in electric cars; The plug-in vehicle payments would go to the first 250,000 consumers to purchase the qualifying 2010 models, Cantwell said. Those consumers can operate their vehicles at the equivalent of about 70 cents per gallon of gas, proponents say, and a study by the Tri-Cities' Pacific Northwest National Laboratory showed enough capacity in the U.S. electric system to support about 70 percent of the country's passenger fleet. "We really want to help drive down that engineering cost and get people who are early adopters to start using the existing electricity grid," Cantwell said, adding that plans to maximize the performance of the grid could further save power. |
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The XFE project began about 18 months ago, focusing on the overlooked ways in which fuel economy can be improved in everyday cars. "Every tenth [of a mile per gallon] counts," explains Al Manzor, Program Engineering Manager for Cobalt and G5, who led the quest for extra mpg. The GM team worked with tire manufacturers to develop low-rolling-resistance rubber specific to the Cobalt. XFEs are equipped either with Goodyear Integrity tires (running at 35 psi), or Continental Touring Contact AS rubber (which specify 33 psi). By adding intake and exhaust variable valve timing to the 2009 model's 2.2-liter Ecotec inline Four, peak power is boosted from 148 to 155 hp, with enough of an increase in low-end torque to encourage engineers to drop the rear axle ratio from 3.74 to 3.63, for improved fuel economy. The taller ratio enables this Cobalt to reach 60 mph in second gear instead of third, and its 0-to-60 mph time remains unchanged at 8 seconds flat. In spite of the tougher EPA certification guidelines in 2008, the highway fuel economy number jumped from 33 to 36, and again to 37 mpg for 2009. A few calibration changes also assist the fuel economy gain, including a fuel cutoff feature during deceleration, which GM engineers emphasize is transparent to the driver.
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Replying to: 62vetteefp (Sep 25, 2008 3:44 am) I note that in a different thread I saw a number of posters talking about how "every car built today" has a feature that cuts off the fuel completely when the car is decelerating. At the time I suspected that was a lot less widespread than they thought it was. And now I see here that it appears no Cobalt had it until they put that feature in the '09 XFE. It would be nice to see them find a way to offer a slightly smaller engine in this car, thereby bringing up that city number, but it is right up there at the top of its class as it is. And I know that next year the Cruze will come along anyway, with its completely different engine and promises of 40 mpg, so that's great.
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Replying to: nippononly (Sep 25, 2008 7:07 am) I'm still on the side that a fuel injection system cuts the fuel off while coasting in gear and I'd like to hear the Cobalt engineers expound on this. Someone please ring them up. 
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Replying to: steve_ (Sep 25, 2008 7:24 am) One other thing to consider though, even if the fuel shuts off completely when you coast in gear, the car will still coast further in neutral than in drive. So in some situations, putting in neutral might still be best.
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Replying to: andre1969 (Sep 25, 2008 7:28 am) When you pop it into neutral, you have to burn fuel to keep the motor running. Plus you have the safety issues of coasting in neutral (and it's illegal most places) and the engine won't run the water pump as fast coasting in neutral so your engine won't run as cool. If you have a carb instead of fuel injection, then the story is different. Or so I've read around here.
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Replying to: steve_ (Sep 25, 2008 7:33 am) I know that if I shut off the engine while decelerating in gear, I won't get the smooth decel I get now leaving the engine running. It will lurch and jump as it rapidly comes to a stop. Or at least, I THINK I know that! 
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