I recently moved to Moraga from Oakland. I used casual carpooling for 12 years in Oakland both as a driver and a passenger. I gave or received hundreds of rides over the years, and I never had an unpleasant experience.
My experience has not been as good since my move. Perhaps casual carpooling is a more recent phenomenon in Lamorinda and people are unaware of the well established etiquette used by carpoolers. Please understand that these are not my guidelines; the following do's and don'ts are adhered to by all experienced drivers and carpool riders:
The driver, of course, is expected to drive safely and cautiously. The driver is expected to provide a relatively clean car interior such that, for example, the riders do not later find cat hair on their coats. It is courteous of the driver to keep the car relatively clutter-free so that the riders have space for purses and briefcases. Drivers typically keep radio volume low and usually tuned to NPR.
Passengers should buckle up immediately. Please assume that food and drink are not allowed in the driver's car. Having said that, most drivers will not care if a passenger brings a cup of coffee if the car has cup holders. After "good morning" pleasantries are exchanged, conversation is generally kept to a minimum unless initiated by the driver. Remember that rush hour driving in the East Bay can be difficult, and the driver may not want to engage in chit chat. A rider who is a smoker should think twice about getting into a car if he or she has just had a cigarette or is wearing clothes that smell of smoke. Similarly, anyone who wears fragrance should wait until arriving at your workplace to apply it.
The standard drop off location in San Francisco is at Fremont and Howard.
Typically, however, the driver will announce his or her destination and allow a passenger to ride farther down Howard or into the Financial District. While it is true that casual carpooling is mutually beneficial - the driver can get into the HOV lane, the passengers get a free ride , and the environment is slightly spared - it is nonetheless also true that the driver is doing the work and paying for the gas, car insurance and wear and tear on his or her automobile. Thus, the driver should not be treated as a chauffeur.
Finally, here is the big one: Cell phones should not be used! I recently picked up a passenger who was on her phone when she got into my car. Traffic was particularly horrific that rainy day, and I was about to ask her to end the call. She then told her caller that she had to get off the phone because she had "a conference call in a minute or two." I thought it was a polite way of ringing off and never imagined that she was serious. I was wrong. She was an active participant in a conference call which lasted throughout the trip, and she refused to end the call even when asked. The other passenger and I were stunned at her obnoxiousness. She was still talking when she got out of the car.
Carpooling is a wonderful concept. I encourage anyone interested to give it a try.
As far as I know, there have never been any significant untoward incidents throughout the history of East Bay carpooling. However, courtesy and common sense make the system work all the better.

Robyn Schanzenbach
Moraga