A new report from U.K.-based consumer organization Which? has criticized car hire companies for confusing their customers with hidden charges and failing to show complete transparency over fees.

According to the report, many car rental companies fail to disclose additional costs until after a booking has been confirmed, making it virtually impossible for customers to identify the best  deals. Of the 120 bookings administered across 10 popular rental websites, researchers said that the total price of car hire was unclear for more than half of them.

In particular, Which? revealed that consumers faced confusion over charges incurred due to excess insurance costs, taxes, compulsory fuel costs and optional extras, such as navigation systems and additional drivers. In a number of cases, these charges were found to double the original quoted cost for the customer.

However, Carrentals.co.uk believes that the prices are normally displayed at the time of making a booking, either in the terms and conditions or in an ”extras” section. 

Commenting on the report, Gareth Robinson, managing director of Carrentals.co.uk, said: "Remember that items such as sat-navs and child seats are optional extras, so the prices for these will not be shown in the overall price, but in an extras section on the website. With regards to fuel costs, try to use a supplier who has a 'pick up full, drop off full' policy in place; that way, you will only pay for what you use."

Robinson added: "Generally with regard to costs, all the information is usually there. To avoid any nasty surprises, make sure you read the terms and conditions before booking to find out exactly what is and isn't included. If you feel there is something unclear, phone or email the supplier for further information."