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
Pembrey Circuit corner and returning to the Start/Finish straight.There were plans to include a quarter mile drag strip, but this never came to fruition. The circuit has hosted the British Touring Car Championship twice, in 1992 and 1993 at which time the championship was the most popular motorsport series in the UK outside Formula One. Formula 3 races have also been run at Pembrey Circuit, and indeed many recent Formula 1 drivers including Jenson Button raced at Pembrey in their early F3 days. Pembrey twice hosted the European Rallycross Championship in 1997 and 1998. Top-level Superbike racing has also been hosted at