Investment companies Knighthead Capital Management LLC and Certares Management LLC have sweetened their bid for bankrupt rental-car company Hertz Global Holdings Inc. /zigman2/quotes/200655672/composite HTZGQ +6.25% and are now offering a deal that values the company at $6.2 billion, the Wall Street Journal reported, citing people familiar with the matter. The investors said their new offer fully covers Hertz's funded debt and has the backing of Apollo Global Management Inc. and existing shareholders. Hertz endorsed a restructuring offer backed by Centerbridge Partners LP, Warburg Pincus LLC and Dundon Capital Partners LLC earlier in April to sponsor its exit from chapter 11. With their new proposal, Knighthead, Certares and their co-investors proposed taking control of Hertz with backing from Apollo, which has agreed to supply up to $2.5 billion in preferred equity financing, people familiar with the matter said. Hertz, which is aiming to exit bankruptcy by end-Juen, did not response to a request for comment.