A buyer is being sought for Wendex Vehicle Rental after the business entered administration.
The company, based in central London, has seen its annual turnover rise from £2.8 million in 2015 to £4 million in 2017, but has run into financial difficulties while awaiting payment from a number of customers.
It hires out nearly 500 vehicles, ranging from taxis through to prestige cars such as Lamborghini, Rolls-Royce and Mercedes-Benz.
Charles Turner, Simon Lowes and Nicholas Parsk, of insolvency and restructuring firm CVR Global, have been appointed as joint administrators and are continuing to trade the business until a buyer is found.
Turner said: "This is a fundamentally profitable business which has suffered from growing pains and cashflow issues partly due to credit control matters.
"With some inward investment and simple operational changes, this is a business that has a bright future with potential to continue on its journey of growth.
"Such is the business's size and potential, it would benefit from integrating with a competitor able to provide stability and address operational issues.
"We have already received several enquiries mainly from competitors and will continue to trade the business until a sale is achieved which we expect to happen imminently."
Wendex Vehicle Rental also operates a vehicle repair workship from its central London base.