I don't know but let's compare that last 2 Gran turismo OVERALL scores to the last 2 Forza motorsport Games shall we...
Release date: NA February 22, 2005
Gran Turismo 4 - PS2
Avg Ratio: 89%
& Release Date: May 3, 2005
Forza Motorsport 1, GT :ZER0 Round 2: Release Date: April 15, 2008
Avg Ratio: 80% & May 29, 2007
Avg Ratio: 90% Forza:2, GT:0 Do you wanna Dispute this? Clearly Forza quality are top notch, Funny how Forza 2 managed to outscore GT5:P when that game came out a year later.. and had time to improve.
Forza Motorsport - XBOX
Avg Ratio: 93%
Gran Turismo 5 Prologue - PS3
Forza Motorsport 2 - X360