According to Kotler, the three main purposes of advertising are to inform, persuade, or remind. Some of the goals of informative advertising are: explaining how a product works, constructing an image for the brand, informing potential customers of services offered, and correcting mistaken impressions.
The following advertisement for General Motors cars is an example of the later goal. Many consumers believe that Japanese cars, like Honda and Toyota, always deliver better fuel economy than American made cars, like GM's products. This ad presents the EPA estimated fuel economy for several GM vehicles in an attempt to show potential customers that their assumptions about the company's cars may not be entirely accurate. The ad does not directly state the comparison to Honda and Toyota, instead opting to talk only about GM's cars, but the suggestion that viewers would be surprised by the fuel economy of the GM vehicles means that the company believes that consumers view the GM product line as being deficient in this area, which would imply a comparison to other companies' offerings.
Cullen Kester, Section G