2011 Chevrolet Volt – Click above for high-res image gallery

General Motors has provided another of its regular updates on the development of the Chevrolet Volt, focusing on its battery and powertrain. With a little over six months to go until the first production model rolls off the line, GM says it is making rapid progress on getting the Volt ready for final validation and certification. Over the past several months, the engineers have been accumulating test miles on the 80 pre-production IVER cars that were built last summer. The fleet has now accumulated over 500,000 miles, with some of the cars having run upwards of 20,000 miles while completing the durability tests.

The durability test cycle is an accelerated test that replicates the wear and tear that typically happens to a car over its lifecycle. According to chief engineer Andrew Farah, the Volt prototypes have met all their goals in both durability and performance. Farah told the attendees that the Volts are regularly hitting the 40-mile electric range target during normal driving, even at temperatures as low as 40 degrees Fahrenheit. Read more about the Volt's status after the jump.

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One of the big questions that people have had since well before GM made an announcement last year that the Volt would get 230 miles-per-gallon on a proposed EPA test cycle is what kind of mileage they can expect once the battery is depleted. While Farah declined to get specific about that number, he did tell us that the engineering team still had the same target of over 50 mpg that has been in place since the beginning of the program.

Farah opened his presentation by emphasizing that the Volt was designed from the beginning as a car that could be built as an affordable, large volume solution. A big part of that affordability equation is that the Volt is likely to be a customer's only car – because of its extended range capability, it is not permanently tethered to the electrical grid. This mention was obviously a knock on some of the other pure battery electric vehicles coming in the next two years from competitors, including the Nissan Leaf and Ford Focus Electric. The lack of extended range capabilities means that those vehicles will not be practical for those that have to drive longer distances. In those cases drivers, will likely need access to a second vehicle.

In the ongoing march to production, the Detroit-Hamtramck assembly plant has now produced six more pre-production cars in the past two weeks as part of the manufacturing verification process. Over the next two months, a total of about 40 cars will be built at Hamtramck. Starting in June, the assembly plant will build about 300 cars that will be part of GM's captured fleet test. This is a standard part of every new vehicle program. These cars will be used by GM engineers and managers on a daily basis look for any other problems that haven't been found during the engineering development process.

Besides durability testing, the other main effort that has taken place over the winter test sessions in Kapuskasing, Ontario, Raco, Michigan, and Summit County, Colorado is development and calibration of the software and control systems. According to Bly, in cold weather, it takes as much energy to heat a human body in the car as it does to propel it. Since the main source of energy is the battery, optimizing the efficiency of the climate control system has been one of the team's primary efforts. That includes finalizing the systems that pre-heat the cabin and the battery. GM's engineers have also spent time on cold weather startup behavior in Kapuskasing to minimize when the engine starts and make it as seamless as possible.

Mickey Bly, GM's executive director of electrical systems, hybrid systems and batteries, discussed the battery testing and manufacturing process that has been ongoing. Working out the supply chain has been a big part of the effort – although protocols have been established for air shipment of lithium ion cells, the primary method used for production will be surface containers. Cells will be shipped from LG Chem's facilities in South Korea to Michigan by sea and land in order to keep costs down. Special containers have been developed for shipping said cells.

Earlier in the day, GM announced that it plans to expand its battery test lab in Warren, MI. The lab will be more than doubled in size in the coming months, taking up space previously occupied by engine test facilities. Those facilities have been relocated to GM's new powertrain development center in Pontiac, MI. The new battery test area will include equipment for cycling many more cells and packs so that additional designs from other suppliers can be evaluated. The lab will also include manufacturing and tear-down test areas. This will allow GM to experiment with the building and recycling of battery packs, something that will become increasingly important in the coming years as more battery powered cars hit the street.

Looking further down the road, Bly said that second-generation Volt specifications would be finalized toward the end of this year. Traditional vehicles have had a four-to-five year development lifecycle, but because of the rapid pace of development on electric drive and battery technology, that is being cut to two to four years for early generations of cars like the Volt. The third-generation Volt will likely be finalized within the next two years, and GM is targeting a 50 percent reduction in battery cost. That will come in part through an expected increase in energy density which will allow the use of a smaller battery without sacrificing electric range.

Overall, the Volt seems to be well on track to meet its production target. The big unknowns at this point remain the car's manufacturing cost and retail price. Nissan has set a very aggressive bar with the pricing of the Leaf, and GM probably won't hit the $25,000 mark (after federal tax credits) that Nissan did, but will no doubt still be aiming for a price under $30,000.

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