Is gasoline price sticky going down?
Yes or no will suffice
At some local markets, yes.
Overall average, no.
You can pick a few select time frames to argue either direction, but I don't see the overall tends following that claim.
If you want to do more specific comparisons, I think the best set of free data is available at the Department of Energy's EIA web site.
Topics for Petroleum Prices
http://tonto.eia.doe.gov/dnav/pet/pet_pri_top.asp