Car insurance costs rose for the first time since 2017, partly because of Brexit uncertainty, according to AA.
Over the past three months, overall policy costs rose an average of 2.7% to £ 609.93.
Premiums also rose because the estimated reduction in claims costs would not be valid until April 2020.
"But what underlies all this is concern about Brexit," insurance director AA Janet Connor said.
He said: "Regardless of what the final agreement looks like, the market continues to struggle with sterling value.
"This has led to an increase in the costs of imported auto parts, further adding to the costs of the auto repair industry which has finally found its way to the premium we pay."
Another key factor is the Civil Liability Bill – which limits whiplash costs.
It is expected to take effect when the bill becomes a law last month, but now it will not be valid for more than one year.
"Although the Civil Liability Bill has now been passed, delaying new provisions until April 2020 means a recent reduction in premiums in hopes that the savings in claim costs along with adjustments to discount rates are premature, explained Ms Connor.
The AA survey echoes similar figures published earlier this month by MoneySupermarket which shows that premiums have reached the highest level since January 2017.
Editor-in-chief of the website Tom Flack said: "It's often more expensive to buy insurance in December because they need more cars so insurance companies don't have to compete as hard as business.
"That means it's more difficult to say whether the increase in the last quarter of 2018 signaled a long-term increase or just a blip."
AA warns that younger drivers feel the biggest difficulty because they have to face an average premium payment of £ 1,317.
Ms Connor said: "Young and new qualified drivers face significant penalties when it comes to insurance prices, at least because they have not yet built a no-claims bonus.
"So it's not surprising that some people risk driving without insurance."
He said the Motor Insurers Bureau (MIB) issued around 3,000 insurance advisory warning letters to drivers who were not insured every day.
John Blevins, pricing expert at Consumer Intelligence, said the black box policy – which uses technology known as telematics – is the best way to reduce premiums.
He said: "Average premiums rose with the fastest rising prices for the top 50s.
"Telematics contributes greatly to keeping prices under control, especially for those under the age of 25 who benefit from adjusted pricing based on good driving behavior.
"If older drivers want to take more control over premiums and to avoid widespread price increases based on their age, they must look at telematics."
AA has called for new drivers using telematics to be exempt from Premium Insurance Tax (IPT) to help reduce policy costs.
"Telematics policies track driver behavior and premiums reflecting individual driving standards," Connor said.
The number of claims made by the driver with the telematics box in their car is up to one third less than that which is not, according to AA.
"Not only will it cut IPT for young drivers who use telematic policies to prevent uninsured driving, it will also improve road safety for everyone," he said.