Actually, I usually got right around EPA in my non-IMA Hondas. My '01 Accord got 23-24 (was rated 20/28) in Chicago metro traffic (think: congested expressways and heavy urban traffic). I moved to a suburban area the last year and a half I had the car - mileage went from 22-23 to 24-25.
I started here because my first tank in the Accord Hybrid was so bad (26-something, IIRC), and wanted to know what I was doing 'wrong'. That car could not be FAS'd, and I did not use extreme drafting techniques. P&G wasn't known to anyone here (except for Kroushl - sp?), so I didn't use that, either.
With the Civic I have now, I still don't FAS the car (also becuase of its tranny), and I don't use P&G - I'm saving that for when fuel supplies get pinched. So I'm not using 'extreme' hypermiling techniques. I also don't draft much at all, because I generally don't drive on the interstate w/ this car.
So what I'm saying is... gonavy's right. The attentive driver can do a lot toward achieving EPA in their car - just avoiding jackrabbit starts can return a good 20-30% increase, as becoming motive from rest is the primary FE killer of an ICE. I didn't coast a lot in the prior non-IMA Hondas (although I did have 'common sense' to lift my foot up when I saw an unavoidable red light up ahead, or try and time it a bit). I was fairly ignorant in those days, and still got EPA or close to it.
The efficiency of the manufacturer's ICE has something to do with what you'll get as well. Some are engineered for FE a bit better than others
Hills do have an effect, I'll acknowledge that. But driving with load can help with that - a lot.