If you are thinking about buying a car and have seen one or two a dealership that you think may be suitable, then you should always try and book a test drive. Most garages will have insurance that will cover you to drive any vehicle on a test drive.
If you have your eye on a few different cars, then do not be afraid to ask if you can drive all of them. A car may look and feel great but sometimes it is only when you drive it that you realise it is not what you are looking for. When you drive two or more cars it is easier to make a comparison and see which one you want to go for. Sales people often work on commission, so they will be trying to get you to buy the car there and then, but you can of course go away and think about it.