While no announcements with regards to the official car list have been made, waging through the videos, screenshots and cars included in Gran Turismo HD Concept have given hint that the following vehicles should wind up in the final game (note that the model year may not be 100% accurate):

# 1991 Acura NSX
# 2006 Alfa Romeo Brera
# 2007 Audi R8
# 2007 Audi TT 3.2 Quattro
# 2003 BMW Z4 3.0i
# 2001 Clio V6 Renault Sport
# 2002 Daihatsu Copen
# 1999 Dodge Viper GTS
# 2006 Ferrari F430
# 2006 Ferrari 599 GTB
# 2006 Ford Mustang GT
# 2004 Honda Integra Type R
# 2006 Infinity G35 Coupe
# 1992 Lancia Delta HF Integrale Evoluzione
# 1999 Lotus Elise 190
# 2004 Lotus Elise 111R
# 1989 Mazda Eunos Roadster
# 2002 Mercedes-Benz SL55 AMG
# 1996 Mitsubishi Lancer Evolution IV GSR
# 2005 Mitsubishi Lancer Evolution IX GSR
# 2008 Mitsubishi Lancer Evolution X
# 2005 Nissan GT-R Prototype
# 1994 Nissan Skyline GT-R Vspec II
# 1997 Nissan Skyline GT-R Vspec
# 2002 Nissan Xanavi 350Z
# 1995 Suzuki Cappuccino
# 2005 Suzuki Swift Sport
# 1995 Toyota Celica GT-Four Rally Car
# 2000 TVR Tuscan Speed 6
# ???? Volkswagen Golf GTI