A car has to smell great not only to ensure that you enjoy your drive but also to ensure that the smell does not percolate your dress or yourself. You will start smelling bad everywhere you go if your car smells bad.
Clean the inside of your car properly. You will need to vacuum the seats, shampoo the stains out and use a scent on the carpet and seats. Any food particle or food on the seat or floor should be properly removed.
Vinegar helps in removing smell. If your car smells badly put it on a level surface and leave it overnight. The bad odor will go away.
You can use a scented candle or fragrance oils under the front seat.
AC can cause a bad smell by forming a scuzz from condensed water. This will need putting chemical cleaners into the air intake and running the engine with all windows open. This will clear the residue from cleaning.
An odor removing spray will help. Make sure that it is sprayed to be damp and not wet. Once dry, you can check the smell of seats or carpet to ensure the smell is gone.
Keep a good car freshener in case any foul smell comes. Car air freshener with a good perfume is an absolute must for the car.
Never leave any food, soiled clothes in your car. They can leave a smell that is hard to remove.