Here, travel expert Emma Coulthurst of TravelSupermarket, reveals the traps holidaymakers often fall into…

Buying at the desk

It’s easy to put off hiring a car until you arrive at your destination. But booking a vehicle in advance – and online – will save you a chunk of cash. It will ALWAYS be cheaper than the arrivals’ hall price and it also means that you have a wider pool of cars to choose from.

The cost of waiting to hire a car in the arrivals hall or at your hotel can be as much as three or more times the price compared with booking online in advance.

The ‘full-empty’ fuel policy

Many car hire companies employ a “full-empty policy”, which means you pay upfront for a tank of petrol and can return it empty. But there are two drawbacks to such a policy.

Firstly, you are likely to be charged an inflated price for the petrol. And, secondly, you may not use all the fuel you’ve paid for if you’re on a short trip or don’t end up driving much. In some cases, you’ll be offered the right to a refund on unused fuel but there is still usually a service charge attached.

Look for car hire firms that allow you to return the vehicle with the same amount of fuel it had when you picked it up, a full-full policy.

Sky-high excess costs

When you hire a car, insurance is included. But you may well find it comes with incredibly high excess charges which is the amount you have to pay to cover the cost of an accident before the policy kicks in. This amount can be up to £2,000 in some cases – potentially leaving you well out of pocket if something goes wrong.

One way to get around the charge is to buy an excess waiver policy, which reduces the charge to zero or a small sum. But don’t wait until you get to the desk! Shop online before you travel and you could pay from around £3 a day, compared with up to £20 if you don’t plan ahead. It is also likely to be better cover than the over-priced policies offered at the rental desks.

One tip: make sure that you take a spare credit card with you which you’re not planning to use during the trip (so that your holiday spending isn’t limited). If you haven’t bought the car hire company’s excess/waiver policy, it will often insist that £2,000 excess is held on a credit card until the car is returned undamaged.

Also, if you are taking more than one car rental trip in a year, it is worth getting an annual excess waiver policy which costs only a little bit more – around £45 – but makes it cheaper than buying it for two single trips.

The ‘upgrade’ option

When you arrive at the rental desk to pick up your pre-booked car, you may be told that the company has run out of vehicles in the category you chose and you may be offered an upgrade – at a price.

Don’t fall for it. You should either be offered a higher-category car for no extra charge or a lesser one with the appropriate refund. Make sure this is the case before you sign your contract and drive away.

Paying for extras you could bring yourself

Want to use sat-nav when driving abroad or think you’ll need a baby seat? Fine – but don’t fall into the trap of hiring them through your car rental company. It’ll be cheaper to bring your own. Some charter airlines don’t charge extra for you to bring pushchairs and car seats.

If your sat-nav doesn’t extend beyond the UK, consider purchasing the additional software or download an app on your smartphone. If all else fails – there’s always the option of a good old-fashioned map.

Unexpected charges when you get home

You expect to return from holiday with a lighter wallet – but it is infuriating to find extra taken off your credit card for a bill you thought you’d squared.

The main reasons for car hire firms to charge more than you expected is when they claim you’ve damaged the vehicle in some way or that you returned it without the agreed amount of fuel.

To protect yourself, give the vehicle a full inspection when you pick it up. Don’t let the car hire firm rush you. Look at the whole car including the tyres, glass, roof and underside of the car. Keep an eye out for pre-existing damage not indicated on the rental checkout sheet and ensure that it is marked on the contract before you take the car away. Take photographs of the pre-existing damage.

Also, thoroughly inspect the car when you return it and ask for a receipt stating it is in good order and has the required amount of petrol.

Hidden charges

Always read the small print of your car hire policy to check for any hidden charges or exclusions.

Some car hire companies, for example, charge extra if you’ve been driving for less than four years, while others charge more for including a second driver.

And others will levy an “admin” fee for theft or damage to the car – even if you’ve bought an excess waiver policy.

Make sure you compare policies online so you get the best deal to suit your needs.

Unlimited mileage

Don’t get a car with limited mileage unless you know you will have low usage. Choose a car hire agreement with unlimited mileage; excess mileage charges can really add up and sting you!

Extra insurances which you don’t need

Car hire companies will try to charge you extra for insurances including personal accident insurance which you might not need. Drivers usually only learn of the price of insurance cover at the rental desk or at the final stages of booking online. It is then generally too late to shop around.

Consumer groups reckon that it is a calculated strategy by the car hire industry to prevent customers from comparing all-in prices. Desk agents working on commission may try to sneak in extra insurances or claim that your own cover is not good enough. Don’t be fooled by them.

You are likely to be covered for personal accident insurance (this pays out if you are severely injured or die in an accident in a hired car) through your travel insurance policy or through the credit card that you used to pay for the rental but it is important that you check this before you go away.

If you are travelling internationally, call your credit card company to see if your destination is covered. If you wait until the desk, you could be charged more than £60 for a week. So, if you need to get this, shop around before you go away.

Overcharging you by asking for payment in sterling

Another trap to watch out for is not being given the option to pay in the local currency when you collect your vehicle – even though firms are legally required to give customers a choice. Paying in sterling can result in you being charged over the odds as firms may use an uncompetitive exchange rate. Before entering your pin number, check the currency being used is the local currency. And, if not, insist it is. This is your legal right.