rabbi, i read the teshuva about trains and buses, where the route runs anyway and i am just one of many passengers, so there is no lifnei iver and no problem. my question is the case where the whole trip happens because of me.

1. the private car. i am not driving, not touching anything, just sitting. but unlike the train, this car is moving only for me. does the train logic still cover it, or is the driver’s melacha now being done for me, and that changes everything?
2. friend vs uber. does it matter if the driver is a jewish friend (now i am causing a jew to be mechalel shabbos, lifnei iver?) or a non jewish uber driver that i hired (amira l’akum, asking a non jew to do melacha for me)? which one is worse, or are both fine?
3. where it matters to me. family i want to see live too far to walk to them, and the shul i want to go to is far from my building. is getting to family or to shul a mitzvah need that changes the din, the way we allow certain things for a mitzvah, or is a want a want?
4. techum and eruv. leaving aside the driver, is there a separate problem of techum for me as the passenger, does my body traveling past the techum matter even if i did no melacha? and is there any difference between riding inside the eruv and riding out of it?
5. the spirit side. even where a heter technically works, does riding around on shabbos defeat the point of the day, or is that itself a chumra people added?

bottom line, can i get in the car or not, and if sometimes, which times?