The driver testing your car will need to be insured, as opposed to insuring your car. The best and safest way to do this is for them to take out a temporary insurance policy. These can last for as little as an hour and offers the same level of protection as a fully comprehensive policy. And if they were to get into an accident, they would be liable for the claim and this wouldn’t affect your no claims bonus in any way.

They may have ‘driving other cars’ on their comprehensive policy, which would mean they could drive your car under their own cover. But this will only cover them for third party damage. So if they do get into an accident, damages to your vehicle wouldn’t be covered, which is certainly the riskier option. So I would certainly recommend asking anyone test driving your car to ensure they have a temporary policy in place so you are covered.