Originally Posted by pkmcd99
Unless you own the 12 with more valves and higher reving then a honda vtec ...
One main, often-overlooked difference, is that, based on the auto-tranny gearing alone, 1st gear in the 2012 auto is geared 19% lower than 1st gear in the pre-12 autos; and 5th gear in the 2012 auto is 20% lower than 4th (the top) gear in the pre-12 autos.
So, my 2012 Jeep auto with 3.73s is geared almost as low as a 2011 auto with 4.56s (the actual equivalent would be 4.49s, which they obviously don't make).
Any helpful pulling power of the 3.6L (even if it's only 10% or so at low revs) adds to that 20% gearing difference. That's why the '12s autos can more-easily spin heavier tires:- engine and
much (20%) lower gearing at the tranny.
The 2012 manual is the same as the 2011 manual. So the 2012 manuals only have the engine difference versus the pre-'12 manuals I think.
2007-12 Manual: 4.46:1
2012 Auto: 3.59:1
2011 Auto: 2.84:1