Questions with 'should the same positioning strategies be used by Hertz the leading national car rental company and a regional rental car company'?

Not quite the same. Hertz is a global company so its strategies can vary from a national or regional that are only going to focus on those areas.. their clients of Hertz and a national and regional company are going to be sometimes the same and here the thing is to differentiate yourself providing a more personalize service than a global company like Hertz or have for example a better support or customer service or discounts, or new functionalities on their website (take a look at: http://www.rentspain.com/) ... There are many possibilities to compete with a large car rental company!