The IndyCar series had invited a number of engine suppliers, along with current supplier Honda, to work on developing a four cylinders- inline - turbocharged engine for the series to be used starting in 2011.
Even thought the meetings were held in secrecy, it is now believed that Audi, Porsche and Alfa Romeo are those manufacturers interested.
Porsche competed in CART in both 1989 and 1990 campaigns, even managing a victory with Teo fabi in '89 but the German Manufacturer quit after it ran into controversy with the other teams when it constructed its own carbon fibre car.
Alfa Romeo, owned by Ferrari, had also a go at CART in 1990 and 1991 but it also ended abruptly after it was unable to develop a proper engine due to the fact that the engine designer started out from an old Ferrari engine that they tried to convert to no avail.
Audi, owned by Volkswagen, is the only engine supplier who has never participated in either CART or IRL series. Still, the German manufacturer has had tremendous success in the Le Mans 24H and in the American Le Mans series.