GM sought tax relief from the city as it reviewed the "business case" for which of its facilities around the world was best suited to place the work.The city council voted unanimously last week to grant two Plant Rehabilitation Industrial Facility Exemption certificates, applied to the Chevrolet building--a 44-year-old facility--and the research and development building, constructed in 1953. The tax certificates will freeze property assessments in those facilities at current rates for 15 years. Two other new abatements at the Technical Center will cut the property tax on new construction by 50% for the next 12 years.

Overall, more than $159 million of the $190-million project qualifies for tax relief. The plan is expected to generate $3.8 million in additional tax revenue for city, county and other tax coffers over the next 12 years. GM, meanwhile, will save between $8 million and $10 million in taxes.

The Warren Technical Center is home to approximately 20,000 GM employees. The 1,020-acre campus is one of two GM global engineering centers in the world.