Mitsubishi has been allied with Groupe PSA since 1999, after they agreed to co-operate on the development of diesel engines using the Japanese company's gasoline direct injection (GDI) technology.[27] They united again in 2005 to develop the Peugeot 4007 and Citroën C-Crosser sport utility vehicles (SUVs), based on the Japanese company's Mitsubishi Outlander.[28]