Yes, drivers of rental cars in Abu Dhabi have the option to drive the car across the border into Oman, but this is the only other country where you may drive your rental car. If you would like to take your rental car into Oman, you must purchase an Oman insurance certificate from the rental car company in advance. You will also need a no-objection letter, which you can obtain from the rental car company. There may be additional charges to take the Abu Dhabi car rental across the border, and sometimes there are restrictions on what type of rental car you can take into Oman from car rental locations in Abu Dhabi.