2007 Civic Hybrid

My 2007 Civic Hybrid has steadily lost miliage per gallon over the 3 years I have driven it. Mostly city driving. When new I got 50+ hwy and 42 city. Recently after a small fender bender the mileage dropped dramatically from 42 hwy/38 city to 37 hwy/34 city. Does anyone have a clue to why the mileage is dropping? I have done all of the reccommended maintenance, at the Honda dealership. The total miles driven is nearly 58,000.

This seems too soon for battery deterioration but, in a hybrid, as the batteries age the gas engine runs a bit longer to recharge.
Have you changed tires recently ?

Could the accident have knocked any battery terminals internaly ?