I think the M5 has done a time of 7:52 if remember correctly.
http://www.rhein-main.net/sixcms/detail.php/1879435?topic_id=731907
Here's a list for some times that I have.
7:28 --- 166.652 km/h -- Porsche Carrera GT, Walther Röhrl,(Autobild July 2004)
7:32.44 163.911 km/h -- Porsche Carrera GT, definitive time by Horst Von Saurma (sport auto)
7:32.52 163.882 km/h -- Gemballa Porsche GTR 600 EVO, Wolfgang Kaufmann (sport auto 2001)
http://www.gemballa.com/news/gtr6002.html
7:36 --- 162.631 km/h -- AC-Schnitzer M3 CLS II E36, 350 hp, Michelin Sport Cup R , Mattias Ekblom
7:36 --- 162.631 km/h -- Porsche Carrera GT, factory test driver Walther Röhrl (2002)
7:40 --- 161.217 km/h -- Porsche GT3 RS, stock but Pirelli P Zero Corsa, Mattias Ekblom, ams
7:40* -- 161.217 km/h -- Porsche Carrera GT, *cold and partially wet track (sport auto 12/2003)
7:40 --- 161.217 km/h -- Mercedes Benz McLaren SLR, Klaus Ludwig (Autobild 07/2004)
7:41 --- 160.868 km/h - Manthey Porsche GT3 M410, 413hp (AutoBild 07/2004)
http://www.manthey-motors.de/nextshopcms/c...spdf.asp?id=217
7:42 --- 160.519 km/h -- Mosler MT900S Photon, Joao Barbosa, 2004 (according to dailysportscar.net)
7:42 --- 160.519 km/h -- Radical 1500 SR3 (2002)
7:43 --- 160.173 km/h -- TechArt Porsche GT Street, 620 hp/1453 kg, (sport auto 08/2002)
7:43 --- 160.173 km/h -- Porsche 996 GT3 RS, factory test driver Walter Röhrl (MOTOR Magazine)
7:43.5 - 160,000 km/h -- Lamborghini Murcielago (Autocar magazine 2002)
7:44 --- 159.828 km/h -- Pagani Zonda C12 S, 580 hp/1820 kg (sport auto 07/2002)
7:45 --- 159.484 km/h -- Gemballa Porsche GTR 600, 600hp (2000)
7:45* -- 159.484 km/h -- McLaren F1, *estimated lap time from a video available at
www.pistonheads.tv
7:46 --- 159.142 km/h -- Porsche 996 GT2, 462 hp/1450 kg (sport auto 06/2001)
7:46 --- 159.142 km/h -- Jaguar XJ220, John Walton (EVO magzine 07/200),
http://www.jwhubbers.nl/ring/docs/evo-0007-7.jpg
7:46 --- 159.142 km/h -- SHK Porsche 993 GT2, 652hp (sport auto 1999)
7:47 --- 158.801 km/h -- Porsche 996 GT3 RS, 381hp (sport auto 03/2004)
7.49 --- 158.124 km/h -- Porsche GT3, 392hp (AutoBild 2004)
http://www.autobild.de/tuning/testberichte...artikel_seite=4
7:49 --- 158.124 km/h -- Porsche 996 GT3 Cup, 360 hp/1207 kg (sport auto 02/1999)
7:49.72 157.885 km/h -- Honda RC30, Helmut Daehne 1993 (moto bike)
7:50 --- 157.787 km/h -- BMW E46 M3 CSL (sport auto 08/2003)
7:50 --- 157.787 km/h -- Blitz Supra, 750hp, Herbert Schürg (1997)
7:50 --- 157.787 km/h -- Lamborghini Murcielago, 462 hp/1450 kg (sport auto 06/2002)
7:50 --- 157.787 km/h - Westfield Super 7 with Hayabusa engine,
http://nurburgring.free.fr/Vids/Bren_Westi...vx504_1_350.avi
7:52 --- 157.119 km/h - BMW M5 (E60), 507 hp,
http://www.rhein-main.net/sixcms/detail.ph...topic_id=731907
7:52 --- 157.119 km/h -- Gemballa Porsche 911 Le Mans (sport auto 1995)
7:52 --- 157.119 km/h -- Lamborghini Gallardo E-Gear (sort auto 12/2003)
7:52 --- 157.119 km/h -- Mercedes Benz SLR McLaren (port auto 06/2004)
7:54 --- 156.456 km/h - Mercedes CLK DTM AMG, 582bhp/1678kg, (sport auto 03/2005),
http://speed.supercars.net/PitLane?viewThr...fID=2&tID=27415
7:54 --- 156.456 km/h -- Porsche GT3 (996) (2003)
7:55 --- 156.126 km/h -- Caterham R500 Superlight, Robert Nearn (EVO magazine 07/2000)
7:56 --- 155.798 km/h -- Ferrari 360 Challenge Stradale, 425 hp/1387 kg (sport auto 02/2004)
7:56 --- 155.798 km/h -- Porsche 996 Turbo, 420 hp/1569 kg (sport auto 06/2000)
7:56 --- 155.798 km/h -- Chevrolet Corvette C6 (company test driver Dave Hill)
7:57 --- 155.472 km/h -- Lotec Porsche 993 Turbo, 600hp/1558 kg (sport auto 05/1998)
7:59 --- 154.822 km/h -- Porsche 997 Carrera S, PASM settino "Performance", (Walter Röhrl WHEELS 06/ 2004)
7:59 --- 154.822 km/h -- Nissan Skyline R33 GT-R, Dirk Schoymans (Autocar magazine 1997)
8:02 --- 154.338 km/h -- Porsche 997 Carrera S, PASM settino "Sport", (Walter Röhrl WHEELS 06/ 2004)
8:03 --- 153.540 km/h -- Porsche 911 GT3, 360 hp/1391 kg (sport auto 08/1999)