My 2008 WRX (5 door, manual, no premium package) had window sticker figures of 18/24. I'm actually getting MUCH better. 23-24mpg around town (within Colorado Springs city limits, but a suburban environment) and 28 or so cooking at 75+ on the highway. The highest mileage was on a mountain trip, 32mpg on a 120 mile round trip on two-lane switchback mountain roads. Speeds ranged from 40-65, and I was driving gently except for a half-dozen spikes passing rolling roadblocks (slow drivers) on the two-lane roads.
I previously had a 2.5i impreza w/man trans, and I figure I lost 2mpg average in the trade-up.