General Motors Co. will invest nearly $332 million in four manufacturing sites to produce more fuel-efficient engines and transmissions.

The investments – announced April 4 at GM plants in Flint and Bay City, Mich.; Toledo, Ohio, and Bedford, Ind. – will support production of a new Ecotec small gas engine, a new V-6 engine, 8-speed transmission, and tooling for an existing 6-speed transmission.

GM also is increasing previously announced powertrain investment in plants in Romulus and Saginaw, Mich., to $646 million – an increase of $46 million – to support production of the new V-6 engine.

Since 2009, GM has announced nearly $1.8 billion of investments for the six powertrain facilities.

“We are investing in technologies and manufacturing capabilities that produce high-quality, fuel-efficient vehicles and components for our customers,” said Diana Tremblay, vice president of GM North American Manufacturing.  “Today’s announcement demonstrates GM’s commitment to growing the business and strengthening the plant communities where we receive so much support.”

GM’s newly announced $331.8 million investment includes:

• $215 million in Flint Engine Operations for a new small Ecotec gasoline engine, which is part of a new family of engines that includes 3- and 4-cylinder variants with displacements ranging from 1.0L to 1.5L. Details of what variants the plant will build will be announced later. The plant will also upgrade tooling for its current V-6 engine. 

• $55.7 million in Toledo Transmission Operations for increased capacity and tooling to produce an all-new, advanced 8-speed automatic transmission and an existing 6-speed transmission. The Toledo-based 8-speed will be used in numerous GM vehicles by the end of 2016.

• $31.7 million in Bay City Powertrain including $19.2 million to produce components for a new V-6 engine and $12.5 million to produce components for the small Ecotec gasoline engine.

• $29.4 million in Bedford Castings including $19 million to produce components for the small gas engine and $10.4 million to produce components for the new 8-speed and existing 6-speed transmissions.

The additional $46 million brings the total to $646 million for the V-6 project including: 

• A $41 million increase to $256 million for Saginaw Metal Castings Operations to produce castings for the new V-6 engine. 

• A $5 million increase to $390 million for Romulus Engine Operations to build the new V-6 engines. 

The new small Ecotec gasoline engine is part of a global engine family that could top 2 million engines a year by the end of the decade, based on production in Flint and other locations around the world, according to GM. The new engines will offer improved fuel economy, higher quality, better performance, and reduced carbon dioxide emissions.

The 8-speed automatic transmission will assist in improved fuel economy and performance. Details about the new V-6 engine program will be announced later.