History of Volkswagen advertising from 1984-90 and difficulties of proving ad effectiveness. VW Golf advertising developed within restrictions of the marketplace. A 'lifecycle' of a new car's performance after launch was developed using predictive model. Assumption that as a new car model ages, demand will drop, only on rare occasions will share continue to rise. On applying model to Golf an unexpected pattern emerged showing continuous rise for seven years. Qualitative research supports role of advertising in this unusual pattern, with attitudes to VW over time showing how the campaigns were working.