Some folks claim that the update made the indicated mileage closer to the
true mileage.  I didn't see any difference.  I get about 39 in heavy city
driving with a 2003 Civic Hybrid CVT.

Is your city travel heavy stop and creep, so that the engine never does
idle-stop?  What do you get on the highway?  How long are you in heavy
traffic?  A few bursts to 50mph tossed in, with heavy acceleration?

I did just get 29.7mpg, but that was from Calistoga to the top of Mt. St.
Helena, a rise of 2200 feet in 15 miles, with four people in the car, and
A/C on.  Average speed about 40mph, due to curves.

Have had the Civic Hybrid for 19 months.  Normal city driving was
showing 32 mpg. Dealer inspected, could find nothing wrong, and
apparently seemed to think I ought to be satisfied, even tho they
advertise 48 mpg in town.

Received a recall on the car, and after talking to the dealer, it
apparently was a software fix for the computer - ahh I thought, maybe
that will help the pathetic gas mileage. Well, it's been a couple of
weeks now since the update and I am presently seeing 29 mpg.