No, you are not required to fill up before returning, as we are happy to refuel the car if it isn’t brought back full. We then add charge the pump price to your card, with no admin fees, no surcharges, no nothing.
If your booking is for an electric vehicle, e.g. the Jaguar I-PACE, then the same principle applies. We charge you at cost for re-charging the car. No admin fees added.