After this post went up, I searched the net and found a list of real-world best times from Nürburgring (mainly to get times to beat when playing GT4, but it seemed fitting for this thread):
6:59 --- Ferrari 312T, Niki Lauda, German GP, training (1975)
7:06 --- Ferrari 312T, Clay Regazzoni, German GP, race (1975) *1.2m longer circuit than standard Nordschleife
6:11 --- Porsche 956, Group C, Stefan Bellof, training (1983)
6:26 --- Porsche 956, Group C, Stefan Bellof, race (1983)
6:41 --- Porsche 956, Group C, Derek Bell 7:50 --- BMW X5 Le Mans V12, Hans Stuck (2001)
*0.232 km longer than current, standard Nordschleife
7:06 --- BMW M3 GTR, 24hrs, test session, Jörg Müller (2003)
7:19 --- Radical SR3 Turbo (2003)
7:20* -- Opel Astra DTM V8 Coupe, set-up for 24hrs race (sport auto 2003) *estimated
7:25 --- Alzen Motorsport Porsche 996, 24hrs race, Uwe Alzen
7:28 --- Porsche Carrera GT, Walther Röhrl, Autobild July 2004
7:32.4 -- Porsche Carrera GT, definitive time by Horst Von Saurma
7:32.5 - Gemballa Porsche GTR 600 EVO, Wolfgang Kaufmann (2001)
7:36 --- Porsche Carrera GT, factory test driver Walther Röhrl (2002)
7:40* -- Porsche Carrera GT, *estimated time on cold and partially wet track (2003)
7:40 --- Mercedes Benz McLaren SLR, Klaus Ludwig, Autobild July 2004
7:42 --- Radical 1500 SR3 (2002)
7:43 --- TechArt GT Street (2001)
7:43 --- Porsche 996 911 GT3 RS, factory test driver Walter Rohrl, MOTOR Magazine
7:43.5 - Lamborghini Murcielago (Autocar magazine, 2002)
7:44 --- Pagani Zonda C12S (2003)
7:45 --- Gemballa Porsche GTR 600 (2000)
7:46 --- Porsche 996 GT2
7:46 --- SHK Porsche 993 GT2, 652 PS (1999)
7:47 --- Porsche 996 GT3 RS, 381PS (996) (2004)
7:49 --- Porsche 996 GT3 Cup
7:50 --- BMW E46 M3 CSL (08/2003)
7:50 --- Blitz Supra, 750 PS, Herbert Schürg (1997)
7:50 --- Honda RC30, Helmut Daehne (1993)
7:50 --- Lamborghini Murcielago (06/2002)
7:52 --- Gemballa Porsche 911 Le Mans (1995)
7:52 --- Lamborghini Gallardo E-Gear (12/2003)
7:52 --- Mercedes Benz SLR McLaren (06/2004)
7:54 --- Porsche GT3 (996) (2003)
7:55 --- Caterham R500 Superlight (2002)
7:56 --- Ferrari 360 Challenge Stradale (02/2004)
7:56 --- Porsche 996 Turbo
7:56 --- Chevrolet Corvette C6 (tested by Dave Hill)
7:57 --- Lotec Porsche 993 Turbo, 600 PS, racing suspension
7:59 --- Porsche 911 Carrera S (997) (Performance Chassis) (Walter Rohrl - WHEELS June 2004)
8:02 --- Porsche 911 Carrera S (997) (Sport PASM setting) (Walter Rohrl - WHEELS June 2004)
8:03 --- Porsche 996 GT3 (1999)
8:04 --- Lamborghini Diablo GT (07/2000)
8:05 --- Ferrari 575M Maranello F1 (12/2002)
8:05 --- Porsche 911 Carrera S (997) (Normal PASM setting)(Walter Rohrl - WHEELS June 2004)
8:06 --- Mercedes Benz SL55 AMG
8:06 --- Caterham 7 Superlight R, Robert Nearn
8:07 --- Ferrari 550 Maranello (06/1998)
8:09 --- Honda NSX-R 3.2 (08/2002)
8:09 --- Ferrari 360 Modena (10/1999)
8:09 --- Lamborghini Diablo SV (no ABS?)
8:10 --- Chrysler Viper GTS, 411PS, UK-Spec, no ABS (10/1997)
8:10 --- Donkervoort D8 180R
8:12 --- Mercedes Benz SL55 AMG (04/2002)
8:12 --- Porsche 993 Turbo
8:13 --- Lotus Esprit Sport 350, 354 PS (05/1999)
8:13 --- Dodge Viper SRT-10, 506 PS (10/2004)
8:15 --- Ruf 911 CTR 2, 520 PS
8:15*-- Holden GTS (2000), *estimated
8:15 --- Porsche 911 Carrera 2 (997) (Walter Rohrl - WHEELS June 2004)
8:16 --- AC-Schnitzer E36 M3 CLS II, 350 PS (11/1997)
8:17 --- Aston Martin Vanquish (2003)
8:17 --- Porsche 996 C2
8:18 --- BMW Z8, 400 PS (08/2000)
8:18 --- Chevrolet Corvette Z05 Commemorative Edition, 344 PS (09/2003)
8:18 --- Ferrari F355 (06/1997)
8:20 --- Audi RS6 (2002)
8:22 --- BMW E46 M3 (12/2000)
8:22 --- BMW M Coupe, 321 PS (10/1998)
8:22 --- Mercedes-Benz C55 (07/2004)
8:23 --- Aston Martin DB7 GT (2003)
8:23 --- Porsche 996 Carrera 4
8:24 --- Subaru Impreza WRX STi (2004)
8:25 --- Audi RS4 375 HP
8:25 --- Callaway C12
8:25 --- Mitsubishi Carisma GT Evo VI (11/1999)
8:25 --- Mitsubishi Carisma GT Evo VII (11/2002)
8:26 --- Mercedes Benz SLK 32 AMG (05/2001)
8:26 --- Nissan 350Z (2003)
8:28 --- BMW M5, 400 PS(also confirmed by Motor Commodore magazine, 2000)
8:28 --- Nissan Skyline GTR, 277 PS
8:28 --- Porsche 993 Carrera 2
8:29 --- Mercedes Benz CLK 55 AMG (05/2000)
8:29 --- Audi S4 4.2 Avant (11/2003)
8:30 --- Maserati Coupé Cambiocorsa (10/2002)
8:31 --- Ferrari F355 GTS, 380 PS
8:32 --- BMW M Roadster, 321 PS (09/1997)
8:32 --- BMW Z4 3.0 SMG (05/2003)
8:32 --- Porsche Boxster S
8:32 --- Volkswagen Golf R32
8:34 --- Acura NSX, 276 PS
8:34 --- BMW Z3 Coupé 3.0i, 231 PS (04/2001)
8:35 --- BMW M3 Coupe, 321 PS
8:35 --- Brabus-Mercedes Benz C V8 Sportcoupé (02/2002)
8:36 --- BMW E36 M3 EVO, 321 PS
8:36 --- Alpina-BMW B3 3.3 Coupé (07/1999)
8:37 --- Maserati 3200GT (2002)
8:37 --- Mercedes Benz C32 AMG (09/2001)
8:37 --- Nissan Skyline GTR V-Spec, 350 PS
8:37 --- Subaru Impreza GT Turbo
8:37 --- Honda NSX 3.0 (07/1991)
8:38 --- Honda NSX 3.2 (08/1997)
8:38 --- Mercedes Benz SL500 (12/2001)
8:38 --- Porsche 996 Carrera, 296 PS
8:38 --- Brabus-Mercedes Benz CLK 5.8 (12/1998)
8:39 --- Honda S2000 (01/2000)
8:39 --- Morgan Aero 8 (04/2003)
8:40 --- Holden GTS, on an in and out lap (2000)
8:40 --- Chevrolet Corvette C5 Targa Automatic (07/1997)
8:41 --- Aston Martin DB7 (1999)
8:41 --- Audi S3, 210 PS (06/1999)
8:42 --- Audi S4, 265 PS (08/1998)
8:42 --- Lotus Exige (11/2000)
8:43 --- Honda Integra Type R (12/2000)
8:44 --- Chevrolet Corvette C5
8:45 --- Chevrolet Corvette, 339 PS, automatic
8:46 --- Porsche 993 Carrera S, 285 PS
8:47 --- Honda Civic Type-R, 200 PS (11/2001)
8:49 --- Jaguar XKR Coupe (07/1998)
8:49 --- Renault Clio Sport V6
8:49 --- Audi TT 1.8T quattro Coupé, 225 PS (11/1998)
8:50* -- Mercedes Benz E55 AMG (2000)
8:51 --- Mercedes Benz C43 AMG (02/1998)
8:52 --- Mercedes Benz CLK 430
8:58 --- Lotus Esprit Turbo SE (07/1991)
9:09 --- Volkswagen Golf V6 4Motion