GM spokeswoman Ryndee S. Carney said the company made the decision in the normal course of making its media buys months ago, before the show made its recent announcement.
"I think it's just a coincidence. I know it's not cause and effect," Carney said.
A group of New York City officials have criticized the new format, saying it promotes divisiveness. They have asked CBS to reconsider its plans.
"How could anybody be so desperate for ratings?" City Councilman John Liu asked last week.
Show creator Mark Burnett said Tuesday that many of those criticizing the new approach haven't ever seen the show and don't understand how it works.
"By putting people in tribes, they clearly have to get rid of people of their own ethnicity," he told The Associated Press during a conference call. "So it's not racial at all."
For the first portion of the 13th edition of "Survivor," which premieres Sept. 14, the contestants competing for the $1 million prize while stranded on the Cook Islands in the South Pacific will be divided into four teams — blacks, Asians, Hispanics and whites.
GM, which has sponsored "Survivor" since it premiered in May 2000, is shifting some of its media dollars from prime-time television to more live sports, awards shows and other big events, Carney said.
The Detroit-based company also decided that its media strategy should feature cars and trucks integrated into shows, which was difficult on "Survivor," she said. Although one episode did feature a Pontiac Aztek, the opportunities for cars and trucks on the show were few, Carney said.
"There's a limited number of possibilities as to how you can integrate a car or truck in a show that people spend their whole time on an island," she said.
CBS spokesman Chris Ender said GM notified the network of its decision long before the new "Survivor" format was announced. He said the company had no knowledge of the competition by race.
"They informed us several months ago that they wouldn't be part of the upcoming season. It's unrelated to the controversy surrounding the upcoming edition," Ender said.
CBS Entertainment, which is part of New York-based CBS Corp., will stick with the format despite the criticism, he said.
Ender would not say if any other sponsors had left the show or if CBS had a replacement for GM.
CBS Entertainment has defended the ethnic twist, saying it follows the show's tradition of introducing new creative elements and casting structures that reflect cultural and social issues.