“The level of precision we’ve achieved [in GT5] is actually more suited to the next generation of machines. The detail that goes into a premium model [has] gone beyond the level of the current PlayStation.”
2010 interview: http://www.gtplanet.net/gt5s-premium-cars-go-beyond-ps3s-capabilities/
The GT5/GT6 assests (new tracks and the premium cars already are PS4 level.