tipping car transfer and taxi drivers

[Kristelle]

We have a car transfer booked from London airport to our hotel and then we will be catching taxi from hotel 3 days later to train station and then taxi in Paris from train station to hotel, and back 2 days later and from Amsterdam train station to docks for river cruise.

 

Car transfer is pre paid, taxi's obviously not.

 

Do we tip and if so roughly how much , would we tip the car driver in cash and can taxis be paid by card and tip added to the card total?