Originally Posted by swizzle
To be fair though, none of the bread-and-butter, mid-sized sedans is substantially different dynamically than the others in the field. Supposedly the Mazda6 is an outlier and a sport sedan to some, but it's just sporty-esque like the rest. Granted, the Sonata is more "Buick" riding than the Mazda6 and its pretense, but the field is pretty evenly matched.
The Mazda6 actually is a fair bit sportier to drive than everything else in the class. It's also a good half-size smaller inside, especially in the backseat, which is a good part of the reason why sales are so sluggish.
I had an Accord before the Sonata, and unless you're daily commute consists of back country roads, there's not a significant difference between the driving experience of the two. The Accord and Fusion are slightly more sporty than a Sonata or a Malibu, but in the suburban/urban cycles most people drive, you'd be hard-pressed to tell much difference in that regard, other than that the Accord's CVT is a half-step in refinement behind the others' geared automatics. I don't think there's a significant difference between those four sedans and the Optima other than personal preferences around styling and equipment. They all drive well, get decent gas mileage, are very reliable and should prove safe in a crash.
As for mileage, mine has been dead on-target with what the EPA wrote on the sticker.