iCarhireinsurance compared the prices of four rental companies at seven popular destinations for the first week of the Scottish summer holidays, 17-24 June 2013, to reveal the hidden costs at the rental desk.

Looking at the destinations of Barcelona, Faro, Malaga, Milan, Nice, Tenerife and Corfu, iCarhireinsurance.com found great variations in the costs that travellers would be paying at each destination.

Car Hire Price (for a small family car e.g. Golf, Astra, Focus etc.) - The cheapest place to hire a car was in Tenerife, costing £89.38 for the week with Budget and rising to £129.03 with Sixt.

In contract, the more expensive place to hire a car was in Faro, where an Astra costs an eye-watering £473.66 from Sixt. Hertz was half this price, at only £227.07, for the same car.

Added Extras: On picking up a hire car, a traveller is confronted with a range of added extras which can sometimes double the original car hire bill.

For example, for someone hiring in Malaga with Sixt, the hire cost for the car is £164 for the week then if they also decide to purchase car hire excess insurance at £77.28, with tyre and windscreen excess an additional £42.42, as well as a child's seat at £42,a sat nav at £39 and finally adding on an additional driver at £39 (or £56 if under £24), these added extras amount to £162 - almost the same price as the original car hire.

Child Car Seat: To rent a child's car seat you could be looking at paying a whopping £82 in Milan to hire from Hertz, while the cheapest place was Tenerife where a child seat cost £16.85 with Avis. In general travellers can expect to pay between £30-£50. Best to bring your own!

Excess Insurance: If excess waiver insurance is not purchased by a hire car customer they could be liable for up to £1700 if the car gets damaged or stolen. Buying it direct from the rental desk could set holiday makers back by up to £144 in Corfu, for instance. This is over £20 a day compared to a daily charge or £2.99 with an iCarhireinsurance.com policy - almost seven times more! An iCarhireinsurance.com policy also includes vulnerable parts of the vehicle, including the tyres and windscreen, which are usually excluded either from car hire companies' policies or insured under yet another expensive excess waiver, For instance, in Barcelona a traveller would have to buy Sixt's standard excess policy at £77, then an additional policy costing £43 to cover the tyres and windscreen excess. This comes to a grand total of £120 or over £17 a day, compared with a single £2.99 a day policy with iCarhireinsurance.com

Ernesto Suarez, founder and CEO of iCarhireinsurance.com said, "Many people choose their hire car provider because they offer the best price, but the added extras can make this a false economy. Excess insurance is one of the most expensive added extra sold at the rental desk, so make sure you don't get caught out and ensure you buy a stand-alone car hire excess insurance policy before you fly."

Sat Nav: This is another expensive added extra, which can cost around £80 to hire for a week in Malaga with Avis, or Hertz charges £82 in Barcelona and Sixt £73 in Faro.

Extra Driver: Adding an extra driver to the policy can seem like a good idea until the cost implications are taken into account. Ranging from over £70 (with Hertz in Malaga and Sixt in Barcelona) to only £12 in Tenerife with Sixt, expect to pay around the £20-£40 mark, however if the driver is under 24 the price rises steeply again up to £118 with Budget for someone hiring in Malaga or Tenerife.

Disclaimer: All prices contained in this article were correct on the original date of publication. Prices may change over time, so for current prices, please get a quote.