Anything is possible in city driving. Cars (non-hybrid) get 0 MPG at idle, 3 to 6 MPG while accelerating from a stop, 10-15 MPG if you're accelerating from a roll, 45 MPG cruising at 40 mph, and infinite MPG coasting in gear. It just depends on your commute.
Try predicting traffic lights. If you think the red is going to turn green, begin slowing down (coast) from far away, so you're still rolling as the other cars are accelerating from a stop. If you're at a light, leave a bigger gap between the car in front of you, and take off early so you can build momentum while still accelerating very slowly. Park and shut off the engine immediately once you've found a spot; don't crawl around in the parking lot waiting for your favorite song to end. Try to brake as little as possible; without regenerative braking, you're just turning precious energy into wasted heat. Plan an alternate route that has fewer stops.
The old EPA city test's max acceleration is 3.3 mph/sec, while the highway test's top speed is 60 mph. If you accelerate to 30 in fewer than 10 seconds, or exceed 60 mph on the highway, your fuel economy will be poorer than the EPA estimates. But then, of course, my V-8 W-Body gets 30 MPG uphill both ways with the A/C on while traveling 70 MPH!!!o~mg!~
YMMV.