Following the announcement a worker at GM's Fairfax plant shines a new Chevy Malibu.

In what is being described as one of the company’s biggest investments since emerging from bankruptcy in 2009, General Motors has announced plans to spend $600-million to upgrade its assembly and stamping plant in Fairfax, Kansas – a move it says will save 4,000 jobs.

The investment will include the construction of a new 450,000 square-foot paint shop, the installation of a new stamping press and other upgrades, GM said.

GM official claim the investment is one of GM’s largest plant investments ever, and builds on nearly $2 billion invested in Fairfax in the last decade. Earlier this month, GM announced it would spend $1.5 billion in North American facilities in 2013. This Fairfax investment comprises a large part of that commitment.

“This major investment is a vote of confidence in the employees and leadership of this plant and will allow them to continue producing beautiful, world-class vehicles like the Chevrolet Malibu and Buick LaCrosse – with the same quality workmanship that has defined the Fairfax complex for nearly 70 years,” said GM Chairman and CEO Dan Akerson.

Construction at the 3.2-million-square-foot plant begins later this year and is expected to take about two years to complete, increasing the footprint of the plant by about 15% to 3.7 million-square-feet. Vehicle production schedules will be unaffected by the construction, keeping the plant’s three shifts of nearly 4,000 hourly and salaried employees on the job.

The plant currently builds the Buick LaCrosse and Chevrolet Malibu both for customers the U.S. and abroad. The investment suggests GM is preparing bot the LaCrosse and Malibu for major changes in the next couple of years.

The Chevrolet Malibu, GM’s primary midsize sedan, went through a complete redesign for 2012. But following a less-than-stellar market reception the maker is reportedly readying what some have described as an “emergency refresh” meant to improve its appeal.

GM’s Fairfax Assembly Plant has a rich and important history in Kansas City, dating to 1945. The plant has employed several hundred thousand people over nearly 70 years, built some of GM’s best vehicles, and, during World War II, was the first industrial facility to make automobiles and fighter planes in the same building.

Since beginning production in Kansas City in 1945, more than 12 million GM vehicles have been built at Fairfax. The current plant opened in 1987 during GM’s flush years.

The new construction will also address some lingering environmental concerns at the sprawling factory.

The all-new paint shop includes substantial upgrades in technology, and will occupy a new building at Fairfax, with new tooling, robots and state-of-the-art environmental and efficiency enhancements. The changes will include to 20% smaller footprint, up to 50% less energy use per vehicle and reduced Volatile Organic Compound emissions.