Due to my job and working time, I’m not able to attend regular prayers in my local Shul - except on Shabbat. Is it permitted and/ or recommended to read the Arvit (in a low voice) while commuting home in the evening, on the bus? In positive case, which parts should I read? (I’m aware of those parts that require minyan, for instance the Kaddish, and those that must be read while standing etc.). This information would be very important for me to take advantage of the transportation time (approx. 45 minutes) to fulfill the mitzvah, and also to keep my mind away from improper thoughts during the trip... Thanks in advance for your clarification and advice.
In your specific case you may pray on the bus as long as you can turn away from any forbidden sights. If you won't be able to pray Shmone Esrei when you get home, you may also pray Shmone Esrei on the bus sitting down. As soon as it becomes possible it would be ideal if you can pray at home [or even better in Shul with a Minyan] and take a good book to read on the bus in order to keep your thoughts in positive places. [נושא התפילה בישיבה ובנסיעה נדון בהרחבה בשו"ע או"ח סעיפים ד-ז ובערוה"ש טו-כ, דעת הגרש"ז אויערבאך זצ"ל בספר הליכות שלמה פרק ח סעיפים ג-ד וע"ע בספר אשי ישראל על הלכות תפילה פרק כג סעיפים ט-יב].