Research by Which? found that drivers could be left in the lurch in situations where they think they are covered by their insurance – but they’re not.

Car problems can be financially disastrous if you are on a low income, or have limited savings, especially if you rely on the car for work – so comprehensive car insurance cover is essential.

But when Which? analysed 73 elements of car insurance across 49 policies from 34 insurers, it found that certain problems encountered by many drivers are not covered by a significant number of policies.

Almost all policies contain some personal belongings cover – which helps you repair or replace loose items damaged in or stolen from your car.

But Which? found that not all belongings are included. Just two policies it looked at protected cash and documents and only three covered credit cards. Four in 10 (40%) policies with personal possessions cover excluded mobile phones.

Legal expenses cover can provide invaluable access to legal advice and funding, but Which? said it can prove toothless in certain scenarios.

It found that only a quarter (24%) of policies will pay for you to recover illegal clamping or towing fees, while just three in 10 (31%) will help you deal with legal costs related to your car’s licence plate being cloned.

Almost all car insurance policies have some provision for courtesy car cover as standard. But only a fifth offer a temporary replacement vehicle if yours is stolen, and just a fifth do so if it is written off.

The rarest feature offered by insurers is guaranteed cover for driving other cars. This type of cover is useful if, in a pinch, you needed to quickly borrow a friend’s car.

While almost all the policies Which? reviewed have a ‘driving other cars’ section, in all but NFU Mutual’s policy, it is not automatically accessible to all policyholders.

Drivers of certain ages (usually under 25) are generally excluded from this cover, as well as those in certain occupations – and in more than a third (37%) of policies, it only applies in ‘emergencies’.

Seven in 10 (69%) policies Which? examined offered help in the event you fill your petrol tank with diesel – or vice versa – but only one in five (18%) will assist with both draining the tank and repairing the engine. Half (51%) of policies do one or the other.

Which? surveyed more than 1,800 policyholders who have made a car insurance claim in the past two years and asked them how satisfied they were with their provider. It also analysed the standard policy of each firm rated.

NFU Mutual topped the table with customers praising the insurer’s ability to deal with queries and value for money. Its total score was 86%. Other top performers included LV (78%), Saga (78%) and Direct Line (76%).

The lowest scores were Admiral (63%), Hastings Direct (65%) and Aviva (66%).

Jenny Ross, Which? Money editor, said: “Our research shows that motorists risk facing hefty bills when things go wrong as a large number of policies don’t cover incidents or possessions you might expect. With the cost of living biting, this means car problems could be disastrous for those on low incomes, or with limited savings.

“We would urge drivers to read the small print. If you’re comparing two similarly priced policies, the bills you can rack up by falling foul of car insurance loopholes could dwarf the extra amount you would pay for the more expensive cover.

“Anyone who’s unhappy with how their insurer has handled a claim should always shop around when it’s time to renew. You could save hundreds of pounds by switching insurers, while getting the right cover to suit your needs.”