If you are going to take on the role of BOB (as a reminder, 'BOB' is the person who does not drink when driving), it is best to use your own vehicle. Otherwise, make sure that the vehicle is in compliance with the civil liability car insurance and has a full omnium (comprehensive) insurance (if possible without excess) so that the vehicle is covered in the event of a claim.
Otherwise, the owner of the vehicle could make a claim against you - the driver responsible - to be compensated for their damage.
There are policies on the market that explicitly cover the case of BOBs. For example, some of these offer to insure you or your family members for damage to the vehicle caused 'as a BOB' (you or a family member drives a third party home in their vehicle) or for damage to the vehicle caused 'by the BOB' (a third party drives your vehicle to bring you or a family member home). Please note! Carefully read the special conditions for the "Bob" cover to be effective. Get informed!