General Motors said it would spend US$449m to upgrade manufacturing processes at Detroit-Hamtramck Assembly and Brownstown Battery Assembly plants to prepare for the next generation of electric vehicles and advanced battery technologies.

The spend, announced at the Automotive Press Association, is the largest to date at both facilities and includes $384m at Detroit-Hamtramck for new body shop tooling, equipment, and additional plant upgrades to build the next generation Chevrolet Volt and two future products. This brings GM’s total investment at Detroit-Hamtramck to more than $1bn over the last five years.

The $65m spend at Brownstown Battery Assembly will support the next generation of lithium-ion battery production and future battery systems.

"General Motors is committed to building award-winning products and developing technologies in America, which helps to grow our economy from a resurgent auto industry," said Gerald Johnson, GM North America Manufacturing vice president. "These investments will help the next-generation Chevrolet Volt build on its position as the leader in electrified propulsion."

Detroit-Hamtramck Assembly Plant is the world’s only automotive plant that mass-produces extended-range electric vehicles – including the Volt, Cadillac ELR and Opel Ampera – for markets in 33 countries. It also builds the Chevrolet Malibu and Impala sedans and is home to a 264,000-square-foot photovoltaic solar array that can generate up to 516 kilowatts of electricity, or enough to charge 150 electric vehicles per day.

Brownstown Battery Assembly’s 479,000-square-foot, landfill-free facility south of Detroit produces the lithium-ion battery packs for GM’s extended-range electric vehicles. It started mass production in October 2010 and is the first high-volume manufacturing site in the US operated by a major automaker for automotive lithium-ion battery production. The site was made possible with the help of American Recovery and Reinvestment Act funding through the US Department of Energy.