If you are booking test drive from a dealership or local garage that last for 15 minutes or so, you can be assured that the showrooms will have satisfactory trade motor insurance to cover you to drive that vehicle in normal conditions
However some test drives can be for a period of days, say over a weekend and sometimes even longer. In these situations you may be asked to complete a separate insurance policy to cover you for this extended period. You should make sure that you are covered for what you intend to do with the vehicle. You should not for example expect to be covered for driving on the continent should you choose to take the car across the ferry for a weekend break.
It may be tempting to allow other members of the family or friends also try out the vehicle whilst ion your care. Before you do, you should check with the garage showroom to ensure that unnamed drivers not on the insurance policy will also be insured to drive that vehicle. You should also ne aware that if the vehicle is used for criminal activity or unusual driving activities that car may not be insured and you may be liable for any costs.
For a normal test dive this will probably not be an issue, but if you have the vehicle for a longer period of time, you may find that the normal breakdown cover options that comes with a new car will be sufficient or advised. Sometimes the garage in question may ask if you are local to ring them first so they can send out their own breakdown cover engineer first and hopefully bring you a replacement car, should the issue be serious. Of course needing any breakdown cover service is unusual in a new car, but again you should check to see if there are any restrictions on the cover provided, in case it only covers drivers rather than car etc. In most cases the garage concerned, will fully advise you on all these issues and give you a contact number just in case you have any problems.