The 6 Cylinder Camry is no longer in production, being replaced by the Aurion range.
Nevertheless, you are right about the 4 vs 6 - there is not much in it
http://www.greenvehicleguide.gov.au/
8.8L/100km vs 9.9 L/100km on combined cyle
12.4 vs 14.1 on city cycle.
(The new Hybrid...