http://toptiergas.com/

The subject Top Tier gasoline has been tossed around from time to time. I never actually knew of any discernible first hand evidence that it is any better than Joe's Outlet Gas, other than a seat of the pants indicator. It seems like a good preventative measure. Especially if the stations are convenient.

Here's an snippet from their site

"Why TOP TIER
The intention of the TOP TIER Detergent Gasoline standards is to create a winning situation for gasoline retailers, auto manufacturers and drivers. Currently, many gasoline retailers provide fuels with lower-quality additive packages that can build up deposits on fuel injectors and on intake valves. Others can build up deposits in combustion chambers and may lead to intake valve sticking. These lower levels of additives can have negative impacts on engine performance and vehicle responsiveness."