I was testdriving 3.0 2007 vs 4.4 2006 models and didnt find major differences in their behavior as far as acceleration goes. Finally decided to get a newer one which now has 1000 miles on it. So far I only found that in the hilly areas the transmission tends to choose a one step higher gear than if I would do it manually. But if I put it into sport mode, it does the selection correctly.