More than 12 million motorists had seen the cost of their motor cover increase by an average of 6% from the last time they bought it.

And 2.32 million would have had it rise by 10 per cent and 1.27 million would have had it increase by over 15%, according to research by Sainsbury’s Bank.

Some of the factors fuelling motorists’ increased car insurance costs may include the impact of compensation claims, uninsured drivers and drivers caught for speeding offences.

As a result, many motorists are finding it difficult to afford their car insurance, which helps explain why just over 10 million have taken action in the past couple of years to keep their premiums down.

This includes 566,000 motorists who have sold their car and given up driving and a further 167,000 who still have their vehicle but don’t drive it because they can’t afford the insurance.

Just over 302,000 motorists claim they have not provided their insurers with all of their correct details in the hope that it will reduce their premiums.

Joanne Mallon, car insurance manager at Sainsbury’s Bank said: ''Competition has increased in the car insurance market which means that if motorists are prepared to shop around they can reduce their premiums significantly, but this does not have to be at the expense of reducing the quality of their cover. In fact simply renewing with your existing provider year after year could see your premiums rise and your quality of cover fall.

''Independent research shows that we are regularly among the top ten providers for offering the lowest premiums and we also offer one of the widest range of benefits including a no claims discount of 70% if you have not made a claim in the past five years.''

Action taken by motorists over the past two years to reduce the cost of their car insurance

Number of people who:
Bought a cheaper policy/one with fewer benefits - 3.6 million
Increased the excess on cover - 3.13 million
Listed someone else as main driver - 2.0 million
Bought a cheaper car - 2.0 million
Removed a higher risk driver from their policy - 1.7 million
Reduced cover to third-party - 1.46 million
Sold their car - 566,000
Not given correct details (eg postal address) to insurance company - 302,000
Given up driving because couldn’t afford insurance - 167,000