Enterprise Holdings is battling allegations in the United States that its policy on recalled vehicles is putting customer safety at risk.
The car rental organisation has been accused by consumer groups of allowing cars under federal safety recalls to be rented before repairs are carried out.
Advocates – including the Centre for Auto Safety (CAS) - are petitioning the Federal Trade Commission (FTC) to bar the practice.
“Only strong FTC enforcement action will stop Enterprise from renting unsafe vehicles to consumers and send a message to all rental-car companies to park recalled cars until fixed,” said CAS executive director Clarence Ditlow.
In a statement Enterprise spokeswoman, Laura Bryant, said manufacturer recalls do not ask consumers to immediately stop driving vehicles in most recalls.
Adding that service bulletins affect millions of vehicles each year that, Ms Bryant confirmed the St. Louis-based company was seeking to improve the speed at which it identifies vehicles with safety defects.
The case – which is also supported by the Consumers for Auto Reliability and Safety - comes three months after Enterprise admitted in a California court its failure to fix a Chrysler PT Cruiser was responsible for the deaths of two California women when it caught fire and crashed.
Jacqueline Houck and her sister, Raechel, died in 2004 in a car on which Enterprise Rent-A-Car had not carried out a safety recall.
While expressing regret at the deaths, Enterprise indicated it might not immediately carry out recalls it did not consider major safety problems.
Under federal law car dealers banned from selling vehicle without carrying out a recall, but no such restrictions are applied to rental-car companies.
“We ought to apply the same logic to rental-car companies,” concluded Mr Ditlow.