I recall reading at the launch of the AU that its 4.0 litre 'Intech' six had the same "cylinder bore spacings" of every Falcon six dating back to the 1960 XK. When I tried to make sense of that, I figured the AU is basically a stroked version of that with various evolutionary bits (like the XE's alloy head, XF's MPEFi, EA's SOHC, etc) added over time.
So to answer the question, the AU is an old fashioned car that heavily dates back to a time when inline six cylinder engines were the norm for every car maker. There is another company which refuses to make V6 engines for its products because of the apparent advantages of inline engines - and that's BMW.
Jack Travis, E-Series Acting President
1989 Ford Fairmont Ghia turbo/GL replica (underway)
1994 Eunos 800M
1990 Ford Laser S