Test drive and km?

Hello can someone tell me how it is with a test drive? Man has to sign some contract due to excess in case of an accident. Is there also something because you are allowed to do so per calendar day only… and so. a lot of km and from km so we will charge you with not buying the vehicle? Have the mini s for 2 days and would like to use a longer distance to test the car. please thank you for your advice