Consumer group Which? has released research that shows the cost of hiring a car on a summer holiday has spiked significantly since the Covid-19 pandemic, with some prices rising by as much as 92%.
The eye-watering figures are the result of car hire companies struggling for cars with depleted stocks meaning supply is struggling to keep up with demand.
Which? also warned consumers to check contracts closely as motorists were regularly getting stung with hidden charges.
Having analysed data on 8,000 week-long car rentals from broker Zest during every August since 2019, Which? said the most popular Europeans destinations such as Cyprus, France, Greece, Italy, Malta, Portugal and Spain were seeing increases of up to 77% compared to 2019.
Slightly more positively, the research did show that prices fell slightly last year.
The most expensive place to hire a car was the US, where the average price came out at £546 a week - a rise of 92% since 2019.
Rory Boland, editor of magazine Which? Travel, said: "While there are deals out there, people should avoid the firms with the cheapest headline prices, because too often they will later be stung by hidden charges.
"Only use a reputable broker or hire firm, so you can ensure you're getting the best possible service for your money."
Tips for drivers included booking online in advance, looking closely at costs for extras such as child car seats, and considering external insurance options.