What location?

I rent frequently from SJC. They could care less about what time I pick up usually. I can pick up early or late and they still honor the rate. However, it is true that they might not have the car class available and make you wait until they can find one.

SIXT charges based on a 24hr block for 1 day. If you pick up later, you can return the same time as pick up (ie - 8pm pick up/8pm return). There should be no extra fees. The system recognizes the billing day as a 24-hr day. Same applies if you pick up earlier - just return earlier.

The system will quote your pricing based on reservation time, but charge based on actual pickup/drop off times.