Sainsburys Bank claims that more than five million motorists only obtained one quote the last time they bought car insurance.
Sainsburys Bank subsidiary, Sainsbury's Car Insurance, discovered the figures in a recent survey.
Furthermore it says that those that do shop around for a better deal could save themselves up to 32 per cent.
Joanne Mallon, car insurance manager, Sainsbury's Bank said: "Competition has increased in the car insurance marketplace, which is why shopping around is such good news for motorists. Nobody should accept a higher premium without first checking what else is available."
The research also found that, of the 15.4 million motorists who claim to have been with their current car insurer for three years or more, 38 per cent said that their premiums increased the last time they renewed their policies. Click here to find out more about insurance.
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