Circuit de Monaco downhill again to a double right-hander called "Portier," named after region of Monaco, before heading into the famous tunnel, a unique feature of a Formula One circuit. (Until 2009 only one other circuit, Detroit in 1982–88, featured a tunnel, but the F1 series now includes racing at the Yas Marina Circuit in Abu Dhabi, which presents a shorter tunnel at the exit of the pit lane.) As well as the change of light making visibility poor, a car can lose 20–30% of its downforce due to the unique aerodynamic properties of the tunnel. The tunnel also presents a unique problem
Okayama International Circuit Co., Ltd. on May 1, 2004, and the name of the circuit was renamed "Okayama International Circuit" on January 1, 2005. On October 26, 2008, the circuit hosted a round of the Formula V6 Asia and FIA World Touring Car Championship. The WTCC race was the first world championship FIA race since 1995. However, it was announced on June 21, 2010 that Suzuka Circuit would host the Japan round of the 2011 WTCC season instead of the Okayama International Circuit. Okayama International Circuit Okayama International Circuit (岡山国際サーキット), named TI Circuit Aida (TIサーキット英田) until December 31, 2004, is a private motorsport