Can I rent a car in May for 3 weeks from your Bahrain Airport branch, drive it to Saudi Arabia and return it to your Bahrain Airport branch?
Renting the car for 3 weeks won't be a problem. The website will tell what is possible. Conduct your search and if the website show results (cars) they are available. For crossborder restrictions look here:-
To view the CROSS BORDER or FERRY terms and conditions. At STEP2 of our 3 step online booking process, alongside the car photo of your choice, there is a link entitled “IMPORTANT INFORMATION”. Clicking on this link will open an additional smaller window, with the terms and conditions appertaining to that particular car/supplier. Choose then the CAR tab and look under TRAVEL RESTRICTIONS
Try a few different suppliers as each supplier/vehicle type may have a different cross border rule.
This is what Sixt say about cross border to Saudi Arabia:-
Cross Border Rentals are on request only. Please contact the local rental station. Contact details can be found on your voucher.
Ok, I will check what my options are.
So I would recommend: Chose SIXT and request cross border at the desk on arrival or by phone once the reservation has been made .