I have a CRX buts is got a B18A motor in it out of a 91 integra LS, so I guess I can post what I get here.

I bought the car with the b18a in it, and the mileage was awful.
Around 12mpg.

After messing around I replaced the o2 sensor and saw that the vacuum lines where hooked up wrong, so I hooked them up right, and of course that helped out a bunch.
I just filled up today, and got 211 miles on 8.2 gallons, so thats about 25-26 mpg. That is all city driving. Gas here in WV is about 3-3.25 a gallon now, so I am glad I'm not getting 12 mpg anymore.