Almost three in every five people (57 per cent) chose their car insurer based purely on the quoted price of the premium.
Only one fifth of people (19 per cent) even worried about the level of cover offered.
One in twenty people said that a courtesy car was paramount, with two per cent of people naming breakdown cover, a discounted rate for partners, a low excess or a protected no claims bonus as offers which would influence their decision.
James Caldwell, director of Fairinvestment.co.uk, said: "Motorists should be careful choosing their car insurance by price alone, the cheapest car insurance is not always the best and there are other aspects to be taken into consideration.
"I would advise anybody shopping for car insurance to compare deals not just on price but also policy features, some of which may be outlined in the small print."
Research by the Financial Services Authority (FSA) has found that many comparison deals do not compare like-with-like, so similar named jobs, such as describing yourself as a journalist rather than a reporter, might cause huge variations in quotes, for example, or even using out-of-date policy products – which give the wrong information completely.