Federal regulators are seeking more assurances that Hertz Global Holdings Inc.’s plan to buy rival car-rental firm Dollar Thrifty Automotive Group Inc. DTG will result in savings for customers, people familiar with the matter said.

On Thursday, Hertz said the Federal Trade Commission asked for more time to review the proposed deal between the two car rental giants. Hertz said it won’t close the purchase sooner than Nov. 16. Previously, the company said the deal could close after Oct. 31.

The FTC is mining data provided by the rental-car companies about potential consumer savings and asking questions about the figures and analysis, one of the people said. An FTC spokeswoman said the agency is reviewing the deal; she declined to comment further.

Tags: ftc, hertz