You must have a valid passport or identity card for all travellers. Before you leave, check the requirements of the different countries you drive through regarding your car, the equipment of your car, health restrictions and the necessary documents. Also check if there are special requirements in case of a pandemic. In many countries vignettes are mandatory, in most cases you can buy them in advance at your National Automobile Club. Also think of safety vests and a breathalyser (in some countries you will need to carry these with you). Make sure you know how to reach your insurance in case of an emergency. Bring policy numbers and contact details with you. Be well informed.