The DFX variant was initially developed for Indy car use by Parnelli Jones in 1976, with Cosworth soon taking over.

This engine won the Indianapolis 500 ten consecutive years from 1978 to 1987, as well as winning all USAC and CART championships between 1977 and 1987.

A 2.65-L turbocharged version of the DFV was developed privately by the Vels Parnelli Jones team for the 1976 USAC season, in the face of opposition from Duckworth.

[12] Unser and his Cosworth-powered Parnelli took two further victories before the end of the year, in Wisconsin and Phoenix, and finished the championship in fourth position.

In 1986 GM financed British firm Ilmor to build a competitor to the DFX in Indy car racing.

Ford responded by commissioning Cosworth to redesign the DFX to include a number of DFR improvements.

However, the Kraco team merged with Galles at season's end, dropped the program, and switched to Chevrolets.

The engine was utilized by other CART teams in 1991–1992, and was retired after the introduction of the Ford Cosworth XB with only one victory, that being Rahal's in 1989.

Ford-Cosworth designed a brand new line of engines for use in IndyCar to replace the aging DFX and DFS.

The XF was developed for the 2000 season to replace the XD, and was chosen as the spec engine for the Champ Car World Series in 2003.

While many teams left Chevrolet after the 2003 season, those that stayed saw a significant improvement in performance with the new "Chevworth" engine compared to their previous units.