Greg Shafer ended a lifelong streak of buying U.S.-made cars when in August the 53-year-old drove out of a Columbus, Ohio, dealership behind the wheel of a Buick Envision.

His $40,000 sport-utility vehicle is one of the first cars to be sold in America that was built in China. Mr. Shafer decided its provenance wasn’t an issue because “once you drive it and experience all the features, it feels far from a made-in-China car.”

As the U.S. auto industry’s rising reliance on Mexican car factories becomes a hot topic in the 2016 presidential election, customers like Mr. Shafer are delivering a boost to General Motors Co. ’s made-in-China strategy.

The No.1 U.S. auto maker in terms of sales started selling the Chinese-built Buick Envision in North American dealerships in late spring, importing relatively small numbers of the vehicles to give a boost to the Buick brand. A few months into the experiment, dealers are clamoring for more because they say most of their customers don’t care where the vehicle is made.

“There has been very little pushback,” said Chris Haydocy, co-owner of the Haydocy Buick GMC in Columbus, where Mr. Shafer bought his SUV. “Most people realize the world is flat now.”