Production stoppages at five General Motors Co. plants signal that the automaker — like its U.S. rivals — will stop building most sedans and small cars.

On the chopping block are six four-door GM cars following the automaker's decision announced Monday to idle three assembly plants and two transmission plants in efforts to save $6 billion by 2020. The Buick LaCrosse, Chevrolet Impala, Cruze and Volt, and Cadillac CT6 and XTS will no longer be produced when GM's Detroit-Hamtramck Assembly, Lordstown Complex and Oshawa Assembly plants go dark next year.

The automaker previously said it will kill off the Cadillac ATS, built at Lansing Grand Rivers.

A handful of sedans remain: GM has not officially announced plans for the Chevy Malibu, Sonic or Spark models. The Bolt sedan, GM's electric vehicle, is currently the platform GM is using for its autonomous vehicle. The Camaro is the brand's halo muscle car. The automaker is in the middle of installing new tooling at its Lansing Grand River Assembly plant to build new Cadillac luxury cars.

GM's decision is the latest response to an ongoing shift among U.S. consumers who prefer trucks and SUVs to the sedans that saved the U.S. automakers during the fuel crisis last decade. Sedans no longer make enough money for the automakers as they try to fund ventures in electrified and autonomous vehicles.

Read: GM stopping work at 5 plants, laying off salaried workers

"You will see a greater share invested in autonomous and electric vehicles," GM CEO Mary Barra said Monday. "Those investments will be seen in engineering budgets and in new global products...This industry is changing rapidly (and) we want to make sure we are well-positioned."

GM officials said work at Detroit-Hamtramck, Warren Transmission, Lordstown Assembly in Ohio, Oshawa Assembly in Ontario and Baltimore Operations in Maryland will idle next year, but plants will not officially close. The future of those facilities will be determined during 2019 contract negotiations with the United Auto Workers.

Oshawa is the only plant building the Cadillac XTS sedan. Detroit-Hamtramck and Oshawa are the only plants building the Chevy Impala. Detroit-Hamtramck is the only producer of the Cadillac CT6, Chevy Volt and Buick LaCrosse as well. Lordstown only makes the Chevy Cruze sedan; the hatchback model is made in Mexico.

Monday's announcements come seven months after cross-town rival Ford Motor Co. said it plans to cut the Taurus, Fiesta, Fusion, C-Max and Focus sedans in the U.S. By 2021 the only car it plans to sell is the Mustang.

At the time of Ford's April announcement, the carmaker planned to import a new Focus crossover to the U.S. from China. It has since scrapped those plans, citing trade concerns amid President Donald Trump's trade war with China. Ford plans to roll out new SUVs and crossovers to replace the sedans.

In 2016, Fiat Chrysler Automobiles said it would pare compact sedans from its lineup, effectively driving higher its sales of SUVs over the last year. The decision to cut money-losing sedans in favor of profit-rich SUVs and trucks has proved lucrative for the automaker.

GM was the last Detroit automaker to signal it was phasing out sedans. In April, Alan Batey, GM’s executive vice president and president of North America, told The Detroit News at a dealer event in Las Vegas that sedans were an important part of GM's lineup.

"We want to lead, not follow," Batey said then. "The team has done a great job understanding the segments, understanding customer preference and price points, and in delivering products that deliver upon that. Will the portfolio continue to evolve? Absolutely. It has to."

Monday's announcement didn't surprise industry analysts.

"This is a big shift in vehicle production, but certainly not an unexpected one," said Karl Brauer, an analyst for Cox Automotive. "The market has largely abandoned traditional cars over the past five years, creating overcapacity at dozens of plants across the industry. General Motors had to commit its future resources where they makes sense, which sadly means a rough end to many employees’ Thanksgiving holiday."

ithibodeau@detroitnews.com

Twitter: @Ian_Thibodeau