Yes, it is preventable if you buy a car that doesn't have it inside of it. As long as companies (or people) are allowed/able to make cars without ads in them,

Yes, it is preventable if you buy a car that doesn't have it inside of it. As long as companies (or people) are allowed/able to make cars without ads in them, then it will be possible. If the government mandates, or market conditions dictate (due to monopolies or insufficient demand/profit incentive), that ads will be in cars, then it will not be possible, at least for new cars.