Longest racetrack in a videogame

Although the Nürburgring Nordschleife is the longest real-life racing track in Gran Turismo 4 (Polyphony Digital, 2004), Gran Turismo PSP (Polyphony Digital, 2009) and Gran Turismo 5 (Polyphony Digital, 2010), the oval test track Special Stage Route X released as DLC for Gran Turismo 5 and Gran Turismo 6 (Polyphony Digital, 2013) runs to 30.28 km (18.8 miles) in length. It consists of two 11-km (6.8-mile) straights. The longest real track is the Nürburgring 24th Strecke at 25.359 km (15.8 miles).