They probably just changed the programming, like Nissan did to the 2.5L diesel in the Navara. Makes a huge difference. The difference between the D4D and the V6 is huge though. Think 4cyl Falcon vs the 4.0L straight six. For my usage ie 99% road with some towing, as a secondhand buyer i'm not sure why you'd buy a D4D Hilux. The V6 uses at most $400-$500pa more in fuel for average annual kM, and 2nd hand for the same condition and age you'll buy one up to $15k cheaper.