Car advertising provides a privileged field to analyze how advertising works, given the weight of the investments, and the level of consumers' involvement. For 10 years, B.V.A. has collected data on several European countries on the impact of the carmakers' advertising campaigns, through its MULTIPACK service. The analysis must separate two kinds of qualities, which can explain why advertising campaigns succeed or fail: perceptive qualities, persuasive qualities. On each dimension, there are wide variations in campaign performances. The level of media investments is only one of the variable which can explain these different performances. Two individual characteristics are of paramount importance: the age of the consumer and the make the presently owns. The leverage effect of advertising campaigns on the purchase intentions of non-owners of the make is much more obvious than the same effect on owners.