score:12
Unfortunately this varies greatly from one provider to the next, and even between individual rental offices of the same chain. Calling them is probably the best choice. Ideally, get a confirmation in writing.
Personal experiences with Sixt:
I had totally different experience with other providers. Asking is good.
Officially they cancel after three hours if you don't call. What happens if you call remains to be seen.
From https://www.sixt.global/php/terms/view?liso=GR&rtar=000&view=EPP&tlang=en_GB&style=typo3
In case the renter fails to collect the vehicle on the rental start date and time without any written or telephone conversation, Sixt will cancel the reservation after 3 hours.
Upvote:2
In the end, I emailed to let the office know that I'd be picking up the car later in the day. There were okay with it and didn't even apply the charge for amending the reservation.
I also reread the rental agreement and found the following which I missed in earlier readings:
The requested pick up time is binding (max grace period of 60 minutes within opening hours).
This means you'd need to check the specific rental location office's terms which may modify the countrywide terms linked in @Hilmar's answer.
Upvote:3
I have asked this exact question to the Sixt representatives some years ago in a similar situation.
Their answer was that they will always keep your car reserved for one hour after your time. After that, unless you have paid in advance, they will try to keep it around, but if there is high demand and they run out of vehicles, they might give it to someone walking in.
Unless you notify them. If you let them know that you are coming later, or at an airport rental if they have your flight number and can see that the flight is delayed, they will also keep your car waiting for you.
tl;dr
Simply give them a heads up. It costs you one phone call and will avoid trouble.
Upvote:12
They will have a limit in their contract how long they wait, and afterwards they are free to give the car to someone else. When you show up after that, you are out of luck.
In practice, they might still give you a car (if they have one!), but I wouldnβt rely on that. You should simply call them and tell them you will be late - you wonβt get any money back for the first hours, but your car will still be there.