Eh, the 370z's are like a full 400lbs or so lighter than a 2010 mustang GT. It DOES NOT feel like a boat. Don't know what you were driving, but it was probably something else with cardboard sides to fool you into thinking you where driving a 370z. The Z is much stiffer than the mustang gt, camaro and definitely the challenger. It reacts much faster to steering input and generally feels more connected to the road than either of the aforementioned cars (don't know if you have actually test drove the 370z, mustang gt - because I have). It is however way more impractical, there is like no trunk/hatch space to speak of and you have only 2 seats. The solid rear axle has it's benefits to drag racers. Alot of the terminator cobra guys swapped to solid rear axles because of the launching problems associated with the IRS. i.e. if you haven't noticed a pattern here - most people with Mustangs want to run their cars on a strip, not a road course.

I will say the mustangs are way more livable than a Z. You have a real trunk, back seats that will come in handy in a pinch (not like they have alot of room). The engines are a bit more tourquey and they will run on regular gas (unlike my 350z and the new 370z's) - not sure how this translates to the new 5.0. The mustang also felt quieter inside and had a better built interior (the 350z interior sucks compared to the competition - qualitywise) - the materials also felt better.

I love the 2010 interior, and the way the car looks - the build quality was excellent (when I went to check them out), the lack of a 6spd on the GT was a turn off for me. I liked the 2010 GT500 alot but dealer imposed premiums (i.e. markups) turned me away. I will definitely be checking the new 2011 GT as a replacement for my Z. The new 5.0will be a awesome engine.

Oh one last thing; Ford sync is fucking awesome.