Many fear there will be significant duplication of charges for the same vehicles as customers pay the charge to return a car and someone taking it out the same day pays the charge again. Transport for London (TfL) will not refund duplications.
Sixt financial director Paul Wildes said: 'Rightly or wrongly the introduction of the congestion charge is with us for the foreseeable future and will certainly have an effect on the rental industry. So much so that we have recognised the need to spell out just how the system will work to all of our customers throughout the UK.
'Each customer has already received information outlining a map of the congestion charging zone, details of charges and the methods of making a payment. These leaflets have also been placed in every rental vehicle on our fleet and together with posters and branch operatives, who have all been trained on how the charge works, we hope to have as little congestion on the administrative side as possible.'
Wildes said the company had employed a dedicated staff member to deal with late payment and penalty fines.
'These charges will unfortunately have to be reclaimed from the customer, who will be subject to our standard £25 administration fee for handling penalty charges,' he added.
Hertz UK general manager Neil Cunningham said he does not expect congestion charging to have much effect on the daily rental industry.
He said: 'We have produced a leaflet explaining the charges and what customers have to do if they plan to drive into the central London charging zone. This leaflet is supplemented by information from TfL. We don't expect that the rental business will be seriously affected by the congestion charge, although we anticipate a small percentage of rentals may shift from locations inside the zone to those on the periphery where customers wish to avoid entering the city and paying the charge.'