The smell of a new car is caused by the outgassing and offgassing of multiple materials and chemicals used in the manufacturing of the vehicle. These include sealers, adhesives, moulded plastics, fire-retardants, paint fumes, leather or carpet treatments, and many other chemicals related to the thousands of components that go into a vehicle. The smell of a new car is therefore unique to the era and model of the vehicle as parts and materials differ between cars and evolve over time.

A new Model T probably smelled like natural rubber, treated wood, and fake leather. Vehicles in the following decades with sealed cabins would block out the rubber smell but hold in the smells related to the upholstery. The first mentions in print of the "new car smell" appeared in the late 1940's in Popular Science, and similar magazines, and it was postulated that the smell came from fumes from lacquers on the interior of the vehicle. As chemistry improved and plastics were added to vehicle interiors in the 60's and 70's, the car smell moved closer to what it is today. New synthetic upholstery, the use of modern glue to seal cabin parts, flame retardant chemicals, and other advances contribute to the changing nature of the "new car smell" to the present.