Aviva found 30% of under 25s admitted to buying invalid or fake car insurance from someone on social media, a scam known as ghost broking.

Upheld driver complaints published by the Financial Ombudsman service lay bare the problems with 'black box' car insurance policies.

Insurers will also be quizzed on those hardest hit by rising car cover costs, including ethnic minorities, those on lower incomes and elderly and young drivers.