Yes - for good quality and thorough level of cleaning your car interiors, you will need to provide access to power for cleaning crew to connect a power based vacuum cleaner.
If power source is not available near your car parking premises, then the cleaning crew will be using a manual approach of removing dust and dirt from car interiors using carpet-grade mop and brush.
Access to about 5 litres of water will also be necessary for the exterior of the car to be washed especially if its thick and stubborn dirt that will be difficult to clean with waterless approach.