If one who regularly prays Shaĥarit or Minĥa is driving a car when the time to pray arrives, she may not recite the Amida because she will not have proper kavana and may even endanger lives. Rather, she should pull over and only then pray.
However, if she is a passenger, and she or the driver is in a hurry to get to the destination, she may recite the Amida while sitting, since if they stop so that she can pray standing, she will be preoccupied with finishing her prayers quickly and will not have proper kavana. Therefore, it is better that she pray Shemoneh Esrei while sitting, since, as we have seen (section 3 above), one who recites the Amida while sitting fulfills her obligation be-di’avad.
Even one who is sitting while reciting the Amida must put her feet together (MB 95:2) and try to face Jerusalem (MB 94:15). At the times she is supposed to bow, she should straighten herself slightly and bow as much as she can (SA 94:5; AHS 18).
When traveling by bus or train, both of which are more spacious than a car, if one can stand and concentrate properly, it is better that she stand for Shemoneh Esrei. However, if standing will disturb her kavana, whether because of the vehicle’s motion or because of the embarrassment in front of the other passengers, she may sit with her feet together and pray. If she is able to stand for a brief time to bow down, she should stand up, bow in the appropriate places, and then sit again. If possible, at the end of her prayer, she should stand and takes three steps backwards. 1
- See SA 94:5. If one has two options, to stand with her feet apart or to sit with her feet together, it is preferable to stand. Similarly, it seems that it is preferable to pray while standing, even if not toward Jerusalem, than to pray while sitting facing Jerusalem (Peninei Halakha: Prayer, ch. 17 n. 12). ↩