Depending on where you are in North Carolina, gas is as low as $2.59 (Sheetz on Capital Blvd, North of Raleigh, NC).
My Father has a Freestyle (same size as a 500) and it is not underpowered - at least compared to other family sedans I have driven recently. I suppose compared to a Charger with a hemi it is slow, but how many people buying a "family" car really need or even want a hemi? According to CR, the 0 to 60 for a 500 is 8.7 sec ( a full second faster than a 4 cylinder, manual Camry and roughly the same as a Chrysler 300 V-6). Not awesome, but certainly not bad either. And it is an easy car to drive quickly. Some cars I have driven have lots of power and are really fast if you floor them, but you really have to work hard to keep up with traffic. Dad's Freestyle seemed effortless. No dramatic actions needed. Generally a really nice, if undramatic car.