Hertz, the car rental company acquired last year by a private equity consortium for $15bn (€11.7bn), has recruited a new chief executive amid continuing threats of a downgrade to its credit rating.

Mark Frissora joins Hertz from Tenneco, a US company that makes shock absorbers and exhausts for cars. Frissora oversaw a turnaround in the fortunes of Tenneco since his appointment as chief executive in 2000, with the company winning awards for the returns it delivered to shareholders.