The annual "3.15" consumer rights day investigative special, similar to CBS network's "60 Minutes" in the United States, also criticized Jaguar Land Rover for gearbox problems in some cars.
China is the world's top auto market, and media criticism can dent reputations and drag on sales. iPhone maker Apple made a rare apology in 2013 after criticism on the show of its after-sales service.
Mercedes and JLR are already being probed by China for possible anti-competitive behavior. The Chinese venture of Volkswagen was fined last year for price-fixing.
Volkswagen, a target two years ago of the China Central Television (CCTV) show, was also criticized in an article ahead of the program for its handling of a recall of its Sagitar car.
"We have paid close attention to CCTV reporting and we sincerely apologize for any inconvenience caused to our customers," said Volkswagen China spokeswoman Larissa Braun.
Nissan's China joint venture said it would set up a team to investigate the allegations and strengthen regulation of its service teams, according to a statement on its official microblog.
Mercedes said it would launch a probe and urged dealers to reform their behavior. Land Rover apologized to its customers on its official microblog and said it was working to resolve the issue.
CCTV itself has come under fire in China over the last couple of years, with some consumers rushing to defend its targets or simply changing channels.
But marketing experts said that without damage control the impact of such shows in China could damage companies severely.
"The 3.15 show still packs a punch to the firms targeted, and a poor or flippant response from a targeted company can evoke consumer outrage," said James Feldkamp, CEO of consumer watchdog MingJian.