Avoid using car fresheners that contain ‘fragrances’, ‘perfumes’ or ‘fresh scents’. These are many chemicals combined that do not need to be listed for ingredients. They often use ‘masking’ chemicals to neutralize smells and odors. Its best to vacuum well the inside of your car, try baking soda, lavender, rosemary, mint or lemon essential oils. Try borax on tough stains or odors and then vacuum well.

Use screens or shades across the windshield when leaving the car in the sun for long periods of time. This keeps the interior cooler and prevents the plastic interiors from heating up and off-gassing noxious smells and chemical ingredients. Heat and UV exposure increases the off-gassing of all the interior surfaces. Use mild or green surface cleaners to wipe down surfaces. 

Keep drinking water in a stainless steel or glass water bottle in the car. Plastic water bottles heat up in the sun and then leach chemicals from their material into the water, making it less safe to drink. If purchasing a new car, choose vehicles that avoid using PVC plastics in the interior and flame retardant and vinyls in the seating fabrics and coverings on dashboards and gearshifts. New car smell is a mixture of hundreds of chemicals off-gassing from the car interior that not only cause initial headaches but long term health issues as well.

Have your air filters in your car cleaned regularly to ensure best and proper air circulation.

If possible, use or find natural fabric or untreated fabric car seats to cover the vinyl, plastic, or car leather (vinyl) seats.

Keep the windows cracked a little when in the car. Mix fresh air in the interior whenever you can.