Complex sentence: Earnhardt-Childress Racing Engines (ECR) was formed in May 2007 with cooperation between DEI and Richard Childress Racing, developing and building engines common to the Chevrolet NASCAR Nextel Cup Series and NASCAR Nationwide Series teams.
Split into simpler sentences: Earnhardt-Childress Racing Engines (ECR) was formed in May 2007 with cooperation between DEI and Richard Childress Racing. The organisation develops and builds engines common to the Chevrolet NASCAR Nextel Cup Series and NASCAR Nationwide Series teams.