Of course, both theologies also require kashrut observance, but this is not a pre-condition for saying Birkat HaMazon . Each mitzvah is another opportunity to experience your holiness, engage in divine service, and elevate the quality of Creation. Since the commandments of congregational prayer and of public Torah Reading are only rabbinic laws, it is clearly better to stay at home and pray alone than to drive a car. No other automobile use on the Sabbath has ever been officially sanctioned by the Conservative movement. In general, it is best to do whatever you can, and to aspire to growth in learning and in mitzvot .
Every mitzvah is 'plus one'.
Even a mitzvah done mechanically is better than if left undone. Each is something to feel good about and has its own reward. So don't dwell on opportunities missed. Any significant practical application of halacha affecting your lifestyle should be undertaken with the assistance of competant rabbinic authority.