DETROIT — In September 2017, General Motors CEO Mary Barra and her top executives visited the automaker’s design dome, considered hallowed ground within the company for its role in creating GM’s most iconic vehicles.

Displayed under the showroom lights were about 10 true-to-size clay models of electric vehicles, including designs like the automaker’s Chevy Corvette and a host of crossovers and SUVs. At the time, much of Wall Street’s attention was on the nearly $400-a-share price of Tesla, whose celebrity CEO, Elon Musk, was promising to lead the world’s transition to more sustainable energy.

The showcase at GM’s sprawling tech campus in suburban Detroit gave executives a glimpse at how they might outpace Tesla and longtime rivals such as Ford Motor, which were also eyeing the buzzy electric vehicle market. The clay models were examples of the range of electric vehicles GM could build through a new platform the automaker was developing.