It’s only supposed to get 26mpg. Spend a lot of time idling in traffic?
I do spend a fair amount of time idling at stoplights, but the 2006 sticker promised 30 city / 40 highway. Don't take my word for it. See:
With the optional five-speed automatic transmission, the Civic is rated at 30 mpg city and 40 mpg highway by the Environmental Protection Agency (EPA).http://www.automedia.com/2006_Honda_Civic_Sedan/rts20051101hc/1
I know that in a traffic-clogged city, my numbers might end up being a bit lower, but they shouldn't be THAT much lower. My old GM vehicle promised 23 city / 32 highway, and I used to average around 24 mpg, so I expected to do at least that well with the supposedly more fuel efficient Civic. Instead, I'm doing a bit worse. No wonder Honda had to reduce their estimate to the 26 figure that you cite.
No, what happened was the fuels started having Ethanol, as mandated by the government at about that time. This reduced the fuel economy by about 10-15%.