At taxi Utrecht - the Domstadse Taxi Centrale is this possible. With the customer card you have a privilige. By showing your customer card you will receive 20% discount on your taxi ride. (not in combination with other promotional rates.)
You can order the customer card in the car. The driver will arrange this for you. So if you make a reservations for a taxi, don't forget to ask the driver for the customer card. You will recieve your personal customer card within 7 days.
The order of your customer card at taxi Utrecht- the Domstadse Taxi Centrale is completely free!