It can all depend on the make and model of your car. Who would love to say yes to a Mercedes Benz dealership lol. The one at the airport is massive. Some of the ones my friends and family have been to in Sydney, and they come recommended:
1. Crows Nest Mitsubishi
2. Ryde Mitsubishi
3. That one in Glebe near Ross Street
All I can comment on as I don't own a car. I drive, but don't need to own a car.