Research by comparison site Gocompare.com revealed that every year 30% of drivers – equivalent to 8.5 million individuals – roll-over their car insurance without checking for cheaper premiums.

The survey found that 37% of drivers have stayed with the same insurer for three years or more, while 18% have stayed loyal to their insurer for five years or more.

Of the UK drivers who rolled-over their car insurance policy at their last renewal, 37% believed that because their insurer was cheapest last year they would offer good value again this year.

Meanwhile, 26% auto-renewed out of loyalty to the insurer, 22% didn’t want to change their direct debit and15% said they had stuck with the same insurer because they thought that it was too much hassle to get new quotes.

Of those not auto-renewing, nearly half (48%) said they shopped around to get cheaper cover, while 38% said they didn’t trust their existing insurer to offer them the best deal year after year.

A third thought that they got a better deal as a new customer, 7% had reviewed their insurance arrangements because their personal circumstances had changed, and 5% had switched because their existing provider had made changes to their policy terms and conditions.

Scott Kelly, head of car insurance at Gocompare.com, commented: “Over the last year we’ve seen some major changes taking place in the insurance market, including gender-neutral pricing and changes in the law restricting the activities of claims management firms, which have resulted in a fall in car insurance premiums.

“September is not only a peak time of the year for car sales, but car insurance renewals too. Many insurers will offer you the chance to simply auto-renew your policy, and while this may seem an easy and convenient option, it could leave you hundreds of pounds out of pocket as loyalty seldom pays.”