Skiers hiring a car could end up paying double, triple or even four times more than they paid for the week's hire on extras at the rental desk.

Hiring a medium-sized car in Barcelona for a week's skiing this winter costs on average £129, but adding on ‘extras’ at the rental desk costs almost £500 on top meaning travellers could be paying out over £600 overall - a quadrupling of their original hire cost. These 'extras', including an extra driver, a ski rack and car hire excess insurance, can often only be paid for when travellers arrive to pick up their hire car.

As well as Barcelona (gateway to Andorra), extra costs at the rental desk will triple the original rental cost in Grenoble and Inverness; double it in Turin, Sofia and Innsbruck, and almost double it in Geneva.

iCarhireinsurance.com, the leading provider of stand-alone car hire excess insurance, researched the costs of five rental companies (Avis, Hertz, Budget, Europcar and Sixt) in the seven European ski gateways of Geneva, Grenoble, Innsbruck, Barcelona, Turin, Sophia and Inverness for a week's hire (13 – 20 February 2016).

The average cost of the 'extras' in all seven destinations were car seat, £49; ski rack, £35; car hire excess insurance, £108; Tyre and Windscreen Excess, £29; an extra driver, £50; sat nav, £72; and a winterisation cost for snow tyres / chains, £32. The total cost of the extras is £375, compared to an average rental cost of £221.

In summary:

• Geneva: Extras at the rental desk cost an additional £430. The average cost for the week’s car rental is £484, giving a final total of £915 – almost doubling the original cost.
• Grenoble: Extras at the rental desk cost an additional £362. The average cost for the week’s car rental is £180, giving a final total of £543 – tripling the original cost.
• Innsbruck: Extras at the rental desk cost an additional £284. The average cost for the week’s car rental is £220, giving a final total of £505 – doubling the original cost.
• Inverness: Extras at the rental desk cost an additional £439. The average cost for a week’s car rental is £167, giving a final total of £606 – tripling the original cost.
• Sofia: Extras at the rental desk cost an additional £218. The average cost of car rental is £131, giving a final total of £349 – doubling the original cost.
• Turin: Extras at the rental desk cost an additional £410. The average cost of car rental is £234, giving a final total of £644 – doubling the original cost.

Car hire prices quoted for hire between the 13 – 20 February 2016

Car Hire Excess Insurance: When driving a hire car in Europe, if a claim is made for damage or theft, the driver is usually liable up to the excess. In this survey the highest average excess liability was almost £2000 in Turin.

On average excess waiver insurance will add over £100 to a hirer's bill if bought for a week from the rental desk, however this cost can rocket. For example, Budget in Innsbruck charge £179 for a week's cover and Europcar in Turin charge £185.

Buying stand-alone car hire excess insurance from a specialist provider, like iCarhireinsurance.com, could save drivers a small fortune. An iCarhireinsurance.com excess policy also includes vulnerable parts of the vehicle, like the tyres and windscreen, which are sometimes excluded from rental company policies. For example in Barcelona, Hertz charge an additional £42 for a Tyre and Windscreen excess policy , which is on top of its basic excess waiver policy which costs £134 - a total of £176. This is over five times the cost of an iCarhireinsurance.com policy costing £32 for the week. Regular travellers might be even better off buying an annual policy for only £45.99.

Roof Racks: An essential piece of kit for many skiers. Budget for around £35 for a roof rack, although the average price in Barcelona was significantly more expensive with an average cost of around £105!

Winter Tyres & Snow Chains: Rental companies often levy a ‘winterisation charge’ covering these during the winter period. The average 'winterisation' fee across the seven destinations was only £32, but can be significantly more.

Extra Drivers: Expect to pay around £50 for an extra driver, rising to £65 in Geneva and £84 in Inverness.

Sat Navs: The average cost is around £70 for a Sat Nav for a week, although some companies charge over £100 particularly in the expensive destinations like Geneva, e.g., Avis charge £110, Budget charge £111 and Europcar £105.

Child's Seat; Expect to pay at least £50 for a child's car seat although some rental companies charge over £100, e.g., in Turin Avis charge £126 and Budget £124. It is worth considering taking your own, specially as most airlines won’t charge to put car seats in the hold.

Ensuring you keep car hire expenses to a minimum should be as high a priority as searching on the internet for the best holiday deal, said Ernesto Suarez, founder and CEO of iCarhireinsurance.com. With a bit of advance planning, costs can be kept to a minimum when you come to pick up your hire car. Always consider car hire excess insurance in advance of travel to avoid buying the expensive rental companies' policies; always pack a sat-nav or use your phone; take your own child seats and keep extra drivers to a minimum.