Four years after the introduction of City CarShare in the San Francisco, Bay area in California, 29% of carshare members had gotten rid of one or more cars, and 4.8% of members' trips and 5.4% of their vehicle miles traveled were in carshare vehicles. Matched-pair comparisons with a statistical control group suggest that, over time, members have reduced total vehicular travel. However, most declines occurred during the first 1 to 2 years of the program; 3 to 4 years after City CarShare's inauguration, earlier declines had leveled off. Because many carshare vehicles are small and fuel-efficient but can carry several people, the trend in per capita gasoline consumption also is downward. Mindful of the cumulative costs of driving, carshare members appear to have become more judicious and selective when deciding whether to drive, take public transit, walk, bike, or even forgo a trip. Coupled with reduced personal car ownership, these factors have given rise to a resourceful form of automobility in the San Francisco Bay area.