Starting in 2016, Tesla produced a run of Model S and X cars equipped with battery packs built to have 75 kilowatt-hours of capacity but constrained by software to have access to only 60 to 70 kilowatt-hours of power. The company began producing cars this way to streamline manufacturing; it could produce the same type of battery but provide different price points, charging customers up to $9,500 for an upgrade to full capacity.

Tesla has since stopped offering the software-limited batteries.

A spokeswoman for Tesla declined to comment, and did not specify how many Tesla owners had benefited from the upgrade.

For Chris Forman, a pilot, the $6,000 discount for a 60-kilowatt-hour battery instead of a 75-kilowatt-hour version was enough to persuade him to spend roughly $70,000 on his Model S in November.

“I never thought I was paying for a car that was neutered — I was paying less to get less range,” he said.

Mr. Forman, who lives in Broward County, Fla., had flown to St. Louis for work on Friday when he checked his Tesla app and saw that his car, plugged in at home, had reached 242 miles of range and was still charging. He had never seen the vehicle exceed 215 miles.

He said he was impressed with Tesla’s initiative, especially given that the company is in the process this month of ramping up production of its Model 3 mass-market vehicle.

“I was totally blown away. It was super awesome of them to do that,” Mr. Forman said of the software upgrade. “Tesla is always thinking outside the box.”