I have a new (< 3000miles) 2004 Dodge Neon SXT (auto trans.). The
sticker said the car should be getting 25-31 MPG. Unfortunately, I
have yet to get anything above 22-23 regardless of my driving
(city/highway/etc).

Being a new vehicle, I don't expect it to be a problem with spark
plugs, O2 sensors, tire inflation, etc. Is there anything else that
can be checked? I fear a trip to the dealer would turn up empty since
22mpg is "close" to 25... however, a previous car with the same rating
easily did 28-30 on average with the same useage and I'd like to
regain something close to that.

Could this really be something as simple as 'heavy-footing' it? Or is
there are potential underlying problem? This car is a bit more
powerful than the last (a 2001 Saturn), so I suppose that could be it
(my wife is quite the lead-foot from a stop..)

Thanks.