Martin Lewis has issued a warning to drivers over “ridiculous” car insurance rules that could see consumers see their payments doubled.

The money-saving expert revealed that insurers determine renewal prices based on “actuarial risk”, meaning the longer you keep your policy, the higher your premiums will be.

He found that some companies were charging as much as 100% to customers who didn’t renew until the last minute.

Martin Lewis told ITV’s The Tonight Show: “It seems absolutely ridiculous, but insurance pricing is all about actuarial risk.

“Their risk suggests that people who buy car insurance early are less risky, so they give them lower prices.

“If you wait until the last minute to get car insurance, you could be paying nearly double.”

According to Money Saving Expert’s analysis of 70 million quotes across numerous comparison sites, the average quote on renewal day is £1,198.

The money-saving expert said the best time to renew your policy is 23 days before the policy expires.

By renewing more than three weeks before the policy expires, drivers can save more than £500 and get a £694 contract.

“It’s not about renewing the offer, it’s about making comparisons to get different offers,” explained Martin Lewis.

He added that even though three weeks have passed, there are still significant savings.