Fiat will use the platform of partner General Motors to build a new large car, Fiat Auto chief executive Herbert Demel said on Tuesday, according to Reuters.

"Last week Fiat and GM signed an agreement according to which Fiat will use the GM Epsilon platform to derive the new upper-medium car," Demel told a news conference at the Geneva car show.

The deal would "significantly reduce engineering costs and investments," he said, according to the report - the new large car is due for launch in 2005.

Fiat's last major car platform-sharing project was for the Croma, a range of large hatchbacks launched in the late 1980s, which shared its platform with Alfa Romeo's 164, Lancia's Thema and Saab's 9000  model lines. All four were in production for about a decade.

Fiat Auto already has a tie-up with GM in its Fiat Powertrain engine joint development operation and also shares the development costs and production facilities for a large minivan line and two commercial van lines with partners Lancia, Peugeot and Citroen.