The most popular car ever made was the VW Beetle with more than 20,000,000 manufactured over a 60 year period.
I had the pleasure of experiencing the appeal of this product first hand, as an owner. Its distinctive form, the reliability of its rear mounted engine with it's unique squil holds wonderful memories of life as a young adult maturing in the 1980s.
If there was ever a product with personality this is one, just ask anyone who owned one.
Video of the History of the Car