Tesla Inc. and Hertz Global Holdings Inc. are negotiating over how quickly Hertz will receive deliveries from a bulk order of 100,000 Tesla electric cars for its rental fleet, according to people familiar with the matter.

Hertz on Oct. 25 said it had placed “an initial order of 100,000 Teslas by the end of 2022.” The press release included no statement from Tesla and Tesla Chief Executive Elon Musk on Monday raised doubt about the deal when he tweeted that no contract had been signed yet.