The 2005 ATS Formel 3 Cup was a multi-event motor racing championship for single-seat open wheel formula racing cars that held across Europe. The championship featured drivers competing in two-litre Formula Three racing cars built by Dallara which conform to the technical regulations, or formula, for the championship. It was the third edition of the ATS F3 Cup. It commenced on 23 April at Oschersleben and ended on 9 October at the same place after nine double-header rounds.
