There are many ways car rental companies can charge you for 'extras' that you may not want or need, and it's not always easy to understand what you're buying.
Which? regularly receives complaints from members about car hire, often in Spain, so before you jet off take a look at our checklist to make sure your rental goes smoothly. You can also check out which are the - and which ones fare badly.
Renting a car can seem cheap when you look at the website price, but that may not be the price you pay. Some initial prices will not include any fuel, and you will be asked to pay more to reduce your insurance liability to zero, or take out extra personal injury cover.
Before you know it, you've paid for all the extras (just to be on the safe side) and the price you now have to pay bears little relation to the one you thought you'd agreed on.
Fuel charges in particular can be confusing and can dramatically increase costs. The next section explains more but in general we recommend you avoid companies that ask you to pay for a full tank of fuel and return the car empty.
It is vital to know how you will be charged for fuel when you hire a car. Different companies have different policies and it's worth finding out what to expect before you arrive at your destination. Options include:
Full-full This is the easiest and usually works out as the cheapest, but only if you return the car completely full. If the hire company feels there's room to add more petrol, you could be hit with a refuelling charge.
When you collect your car, ask where the nearest petrol station is so you know where to refuel at the end of your journey. Also make sure it will be open if you return the car late at night.
Full-empty This option is probably the most expensive, as you won't be refunded for any petrol you don't use. It's not easy to return a car with an empty fuel tank so you're bound to lose out.
Also, the petrol provided may be charged at a premium, which means you'll pay more than you would at a local petrol station.
Same-same This might seem an attractive choice, but make sure you return the car with the same amount of fuel as when you collected it, or you may be charged a premium for the company to make up the difference.
If you choose the best value 'full-full' policy, be aware that there are often penalties if you don't return the car with a full tank of petrol. These penalties are particularly harsh in Spain (see below). As well as paying over the odds for petrol, there can be a fine of up to €50, which the car hire companies say covers preparing the car for the next customer.
Some companies will also fine you if you can't produce a receipt for fuel from a petrol station nearby - so always keep hold of your final fuel receipt.
Which? Travel looked at over 40 contracts from some of the major providers and found several issues to look out for. Always check your contract for the following:
Some car hire companies add on an extra charge if you travel further than a set amount of miles per day. For example, if you drive further than 60km (37 miles) per day with Firefly in Spain, you will face a €0.45 charge per additional kilometre travelled. If you travelled 100km (62 miles) a day, then a week's hire would cost an extra €126.
Any accidents involving damage to the hire car are subject to some surprising admin fees. Some companies charge as much as €150, on top of the price of repairing the damage.
Speeding and parking fines on holiday can also cost more than you bargained for. In the UK, admin fees for processing traffic violations can cost as much as £50 per incident.
Some car hire companies apply an 'exceptional' cleaning charge of up to €242. Always demand photographic evidence of the stain or water damage in question.
Turn up just one hour late to the rental desk and your pre-booked, pre-paid hire car may no longer be available. Not only might you have lost the car and the money that you paid online, but you now also face finding an alternative car at inflated 'walk-up' prices.
Always enter your flight details at the time of booking. Staff are then alerted automatically of delays and should not rent your car to another customer. If you're not collecting from an airport, make sure you allow plenty of time to arrive and inform the office of any delays.
While many companies give you a 'grace period' for returning the car, it can be as little as 29 minutes. Thereafter, a daily rental charge applies, plus a processing fee in some cases.
Car hire companies calculate charges in 24 hour blocks, so if you rent a car at 1pm on one day, but intend to return it at 10am a few days later, still give a return time of 1pm. Doing so gives you some leeway at no extra cost.