Martin Lewis issues urgent warning for Britons travelling this summer

The financial expert said that customers could be encouraged to pay when they pick up their rental car.

He said:"Car hire usually includes basic insurance, yet at the pick-up desk, they almost always try to push you to get 'excess cover insurance' costing up to £25/day using scare stories of huge bills for just a scratch - or sometimes implying you have to do it."

Lewis suggest drivers should instead buy insurance in advance as it could cost as little as £2 a day - a potential daily saving of £23.

The expert also warns people that the pick-up desk may try to discourage some holidaymakers by claiming the insurance which was pre-purchased won't work.

Some could even ask Britons to leave a refundable deposit of £1,000.

The MSE team said not to worry about this: "Not a problem, as long as you have one, just keep calm and carry on."

Lewis advises people to find cheap car insurance by using comparison sites such as MoneySavingExpert, Compare the Market or Go Compare.

He added to try and get in as early as possible as it will mean people will be able to take advantage of the best deals.

New data found that holidaymakers heading to Spain and Portugal could save up to £150 by cancelling and rebooking reservations made earlier in the year.

Holidaymakers should check paperwork for the cancellation terms as the rules vary by country and by company.

Drivers could also save up to £200 in some holiday hotspots by booking with firms or branches based outside the airport.

The Money Saving expert also urged people to avoid hiring extras such as satnavs or children’s car seats, which can cost more per week to rent than they do to buy new.

Many airlines will let holidaymakers check a child’s car seat into the hold for free.