Highly fragranced car perfume in a choice of  lots of different fragrances.
Like no other shop bought fresheners. These are built to last and impress as soon as you open your car door. 
A slight tip upside down every few days is all that is needed to soak the cork again and emit the yummy scent all around your car. 
Reminder - follow instructions and remove plastic cap stopper before hanging in your car.