(CNN) — Fly-drive holidays give travelers the freedom to explore a destination at their leisure, but it pays to choose your car hire firm wisely.

Now an annual survey by consumer group Which? makes that choice easier by revealing the best and worst companies in Europe.

Spanish firm Goldcar came in bottom of the rankings for the fifth time in six years, according to a Which? press release.

Complaints about the company include rude staff, pressure selling techniques and surprise charges. Some 38% of customers said they would definitely never consider using Goldcar again.

The company offers cheap headline prices -- £13 ($17) a day on average -- but 40% of customers reported a problem, with the majority citing shock credit card charges or poor customer service.

A buyout by industry giant Europcar had raised hopes of an improvement but the overall customer score actually declined to just 39% in the 2019 survey.

A spokeswoman for Goldcar told CNN via email that in the past its "customer service has not been good enough and we are determined to fix this."

"In the four months since this survey was undertaken by Which?, we have been actively working to improve our customer service, including improved training and the strengthening of our complaints process, to ensure we are reaching a resolution with our customers as quickly as possible," the spokeswoman continued.

"This is an on-going process and we are committed to making the operational and cultural changes needed to deliver for both our existing and new customers," she added.

Respondents to the survey were asked to rate companies on a number of factors including clarity of extra charges, clarity of final hire cost, description matching reality and value for money, as well as providing the average price per day for their booking.

Europcar also owns InterRent, another budget brand, which came in second from the bottom of the table, and the parent company is also the worst performing of the major car hire brands.

A number of customers claimed that Europcar had overcharged them for damage, and a UK Trading Standards investigation into artificially inflated repair charges for minor damage is ongoing.

CNN has contacted Europcar for comment.

Overcharging for damage is a common problem in the sector. Last year a Which? investigation found that some companies inflated prices by as much as 300%.

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At the top of the ranking sit Cicar (Canary Islands Car) and AutoReisen, two local operators in Spain's Canary Islands.

Customers were happy with the all-inclusive pricing and free additional driver offers.

Among the larger firms, Enterprise and sister company Alamo were top performers in the survey that covered 2,178 car hire experiences among Which? members from January 2018 to January 2019.

"One wrong turn at airport arrivals could easily make or break your holiday. In an industry dogged by unscrupulous practices and interminable add-ons, making the right choice is paramount, so it is good that customers can rely on companies like Cicar and Enterprise to deliver a quality service," said Rory Boland, Which? travel editor.

"Our advice is don't fall for headline prices, vet your car hire firm and whatever you do, avoid Goldcar -- it could end up not being a bargain at all and leave you wishing you'd stayed at home."

Best car rental companies according to Which?

Cicar

AutoReisen

Alamo

Worst car rental companies

Goldcar

InterRent