embarrassingly bad mileage... REALLY

[XYaris]

So I live in Brooklyn. Almost all of my driving consists of short trips within the city. I do spend a decent amount of time idling (when picking up the girl) and I also let the car warm up a bit. BUT STILL...

20mpg consistently. WTF?

Im frankly worried at this point. I check the oil, fine. I even took a trip north out of the city about thirty miles and considering I hit some traffic both directions, I was comforted by getting over 30 mpg on the trip.

I know the idling is a waste, and its cold out, and I make a lot of short trips. yadda yadda

Ive even drastically altered my driving habits by keeping the rpm below 3000 as much as possible. This engine is kinda tiny and frankly feels ridiculously underpowered at these rpms- do people get this great mileage (40+ in th city?!) by just farting around at 2000rpm?

Not looking to get grilled here, just curious if anyone thinks or knows of an issue I may have. Maybe I should get an ecu reflash, or is my youthful exuberance getting the best of my fuel economy?

(2009 LB 2500 miles, only mods are the 205/40/17 pnero zero m+s tires)