Reuters Newsagency quotes an interview Dr Winterkorn, above, gave to the German business publication Manager Magazin as saying he believed Porsche sales could be doubled beyond 2012 or 2013 with three new models, including a “cheap” sports car to sit under the Boxster.
This has raised speculation that Porsche could develop an entry-level sport car based on the Volkswagen BlueSport concept, which has been languishing within VW, despite obvious credentials, including an environmentally friendly diesel engine.
The other models under consideration was a sub-Cayenne SUV, probably based around the VW Tiguan/Audi Q5, and another model of the Panamera, rumoured to be a two-door coupe.
Dr Winterkorn also confirmed that VW could be interested in a tie-up with Japanese company Suzuki Motor Corporation.
"Suzuki would be an interesting partner because of its competency in small cars," Reuters quoted him as saying in the interview.
Volkswagen, Europe's biggest carmaker, was not immediately available for comment, while Suzuki had no comment.
Reuters quotes a person familiar with the matter said there had already been talks between VW and Suzuki.
The magazine said, without citing sources, that Volkswagen was interested in taking a 10 per cent stake in Suzuki or forming a joint venture. It said French carmaker Renault had also in talks with Suzuki, although Renault made no comment.
Suzuki CEO Osamu Suzuki had last told media in late June that he had had no contact with VW, shooting down a Manager Magazin report at the time that Europe's largest carmaker was exploring a deal with its Japanese rival to boost its presence in ultra small cars.
In the magazine interview, Dr Winterkorn defended the terms of VW's deal to buy an initial minority stake in Porsche's sports car business for up to 3.3 billion euros (US$4.65 billion) as a step toward a full merger of the carmakers.
"We are not giving away any money here," he said, adding several investment banks and auditors had confirmed it was paying a fair price in the deal.
The transaction is set to make Porsche the 10th brand in Volkswagen's camp, which ranges from small cars to heavy trucks.
Dr Winterkorn said he could imagine Porsche's annual vehicle sales doubling to around 150,000 units "in the foreseeable future, say 2012 or 2013" as it adds more models.