A survey by iCarhireinsurance.com found that two-thirds (65%) of people who hire cars said extras sold at car rental desks are over-priced. However, more than a third (39%) buy excess insurance from the rental desk, only a third (33%) of parents use their own child car seats, and only a quarter (26%) take their own sat-nav.

According to the study, the average price to hire a medium compact car (such as a VG Golf or Peugeot 308), for a week in Europe is about £500, based on prices from Sixt, Hertz, Avis, Budget, Enterprise and Europcar.

However, once extras are added, such as an extra driver (average cost of £62), a child’s car seat (£56), a sat nav (£86), and excess waiver insurance (£186), the average price increases to £890.

Drivers can save more than £300 by taking these extras abroad with them, or buying in advance.

More than two-thirds (68%) of car hirers said that the rental companies’ headline price for a hire car is often misleading. A similar number (70%) said that rental companies make it hard to find the overall total cost of the hire, including the extras, hiding the information until the end of the booking process.

The cost of all these extras can vary by hundreds of pounds in different locations, from different providers, so it pays to shop around.

The annual iCarhireinsurance survey of car hire costs in Europe found that the average weekly cost for a child’s car seat was £56 – but Budget in Munich charges £88. Also, while the average price for an extra driver is £62, Hertz in Geneva, charges £118; and while the average price for a sat-nav is £86, Avis in Geneva charges £158.

Excess waiver insurance is the most expensive extra cost at the rental desk and almost two-thirds (61%) of car hirers described it as a ‘rip off’. These policies protect drivers from the excess cost if their hire car is stolen or damaged.

Rental companies often sell three excess policies: super damage waiver, super theft waiver and tyre and windscreen excess. These cost on average £134 for super damage waiver, £14 for super theft waiver, and £38 for tyre and windscreen excess, a combined average total of £186.

Drivers can save money by buying a car hire excess policy from a specialist provider before they travel. iCarhireinsurance.com sells a week’s policy for £27.92 for European cover, while annual policies are available from £42.99.

Ernesto Suarez, founder and CEO at iCarhireinsurance.com, said: “It’s surprising that so many people still buy car hire extras from the rental desk, when it is possible to save so much money taking them with you, and buying excess insurance from a specialist insurance provider. The price of hiring a car has rocketed in the last couple of years, but there are still some good deals to be had if you shop around.”