I would suggest using 3M micro-finishing compound. Due to the age of the paint on your car--I would do it by hand if its the just the roof that needs attention. You could use the compound by hand applying with a clean sponge. Do a small area at a time, working the compound into the paint. Before the compound drys--use a clean cloth and continue rubbing till the product is gone. Rinse the sponge out with water as you go along and change or flip the rag often. After compounding--use a qaulity liquid handglaze--3Ms or Mequires--both excellent products in the same way--clean sponge to apply and clean cloth to remove and buff. The handglaze will bring the gloss back up--the compound is more of a cleaner/leveler. After handglaze--if swirl marks are persent--you could use a swirl remover--although you really should need it when working by hand. If touching up with paint is rqd for the deep scratches do it after the handglaze. The last thing would be to apply a coat of polish/wax of your choosing--good luck and do this in the shade