to Smurf without a car?
 

HI, need to get to SMF (the sacramento airport) from SF. Don't have a car. Would appreciate suggestions on the most economical way to accomplis this. Thanks!

Greyhound, alas, has the most frequent service.

Other than that, there's Amtrak and Capitol Corridor train service -- you typically have to take an Amtrak bus or BART to the east bay to catch them.

These just get you to downtown Sacramento, then you have to take a shuttle to the airport, which isn't that cheap.

Finally, there is at least one shuttle service from SFO/SF. Take a look at http://www.shuttlecalifornia.net/

You can sometimes add the SFO-SMF leg to a trip for not too much.

Yolo County runs buses from Davis and Sacramento to SMF. You might see if you can connect with either of those routes.
http://www.yolobus.com/m3.html

Looks like the Yolo County bus to SMF goes right by the Greyhound terminal and costs 42, so yes there is a connection, but note that this bus only runs hourly.

From the Amtrak station, appears to be about a 4 block walk.