Extensions are usually straightforward and don't require returning the car. With most corporate rental companies, you just notify them before your current contract expires - typically 7-15 days notice - and they process the extension. With Octane Rent, I've extended twice by just WhatsApp message to my account manager, and they send the updated contract via email to sign electronically. The car stays with you, monthly rate usually remains the same. Check that discussion
https://www.reddit.com/r/UAE/comments/1qdftr2
where extension experiences are shared. Some companies might increase the rate for extensions or require minimum extension period. Negotiate extension terms when signing the initial contract so you know what to expect. For open-ended stays, month-to-month renewals give you maximum flexibility but might cost slightly more than committing to longer terms upfront.