Cart champion Gil de Ferran believes there is not room for two series

Cart has made the decision so that teams can compete in both series from next year.

And it hopes that the previously-made decision to run the same type of engines as the IRL will keep manufacturers Toyota and Ford in the Cart series.

Cart has been struggling increasingly since the split between the two series in 1996, when Tony George, owner of the Indianapolis Motor Sppedway, set up the IRL.

George's move deprived Cart of its highest profile event, the Indianapolis 500.

Cart teams initially professed their intention to manage without the event, but an increasing number of them have been taking part in it in recent years.

And Cart has been dealt a bodyblow this season with the decision of its most famous and successful team, Penske, to jump ship and compete exclusively in the IRL in 2002.

Plea for support

Cart hopes that the rule changes will shore up support for the series.

"Our goal [is]... to reduce costs and improve the racing while taking into account the current state of open-wheel auto racing in the US and at a global level," said vice-president of racing operations John Lopes.

"We will now shift our efforts into working with existing and potential manufacturer suppliers and teams to join us as we take Cart Champ Car racing to another level."

Cart champion Gil de Ferran, who drives for Penske, has said he believes the two series have to join forces if they are to survive.

The Brazilian, who has won the last two Cart titles, said: "I think we're going toward a different period where there isn't enough room for two series.

"There's not enough investment, not enough sponsorship out there to sustain everybody.

"And that split will continue to hurt both sides. Hopefully this [Penske's move] is an opportunity to get everybody together."