A lot of gas is wasted in the san fransisco area by dirty fuel delivery systems.
Let's start at the tank. The gas tank gathers dirt, rust and sediment over the years. That's why there's a fuel filter to clean the fuel after it leaves the tank. A dirty filter will rob the engine of the clean gas it needs to run efficiently.
The fuel intake components get coated with gum and varnish over time. This results in fuel being delivered inefficiently and some of that gunk getting into the engine. A fuel system service at AskPatty.com, Inc will leave your intake as clean as a whistle.
The big fuel thief is dirty fuel injectors. They deliver fuel to the engine at a specified pressure and in a particular spray pattern. When they're clogged, the fuel doesn't get atomized the way it's supposed to and doesn't get burned as efficiently.
See your owner's manual or ask your san fransisco service advisor at AskPatty.com, Inc when a fuel system cleaning is recommended.