DETROIT—The president of the United Auto Workers union warned automakers that the union is prepared to strike if it doesn’t get its way in upcoming contract talks.

DETROIT—General Motors will expand production and sales of the Chevrolet Bolt electric vehicle. At the same time, GM is expanding battery production for the vehicle from South Korea to a new factory in Michigan.

WARREN, MI—General Motors engineers have developed a technique to join steel to aluminum with resistance spot welding.

DETROIT—General Motors is turning its employees’ recycled water bottles into noise-reducing fabric insulation that covers the engine in the Chevrolet Equinox. The bottles—collected from five of its Michigan facilities—are also being turned into air filtration components and insulation for winter coats for the homeless.

WARREN, MI—General Motors is planning to invest $1 billion to renovate its 60-year-old Tech Center campus here.

TOLUCA, Mexico—GM’s assembly plant here will get part of its electricity from wind turbines.

DETROIT—General Motors engineers are planning to use material from diapers to simulate snow in tests of vehicular heating systems.