Fastbacks are an acquired taste...and even then, there's an element of scale that seems to work best. Smaller being better. The 1965 Mustang worked. The much larger 1965 Rambler Marlin, to my way of thinking, didn't.
While BMW's supposedly adding a fastback to the 3-series in 2013, the current crop of fastbacks are larger cars...four-doors at that...and, well...I think I've made myself clear.
Acura would like us to think that the ZDX breaks new ground between sedan and crossover. That's a pretty slim territory, and a station wagon is what would fill it. One based on the outstanding 2010 TL-SH AWD sedan (review coming soon...I liked it much more than the supposedly identical 2009 and we'll explore why) would be perfect. It would carry more, have better rear and side visibility and handle better than the awkwardly proportioned and heavier ZDX.