Suppose the neighbor wants to move the car out to the street in order to leave,
but it isn't urgent for him to return the car to the parking spot.
Are you allowed to ask him to move the car and return it to the parking spot, or is that already really causing him to stumble in something that has nothing to do with him? (And maybe you even need to ask him not to return it.)
And if it's a matter of saving a life because the car is stuck in the road, then obviously you should do it yourself.

I didn't understand a thing.

When he moves my car out to the street so that he can leave, he's doing it for himself; it has nothing to do with me.
But he has no interest in returning my car from the street to the parking spot.
Am I allowed to ask / hint to him to return it too? He would be desecrating the Sabbath for me, and he has no interest in it.

In my opinion it's forbidden. Let him park in some permitted place and turn off the car. True, I wrote in an article that causing a secular person to stumble (someone who doesn't believe and isn't bound by Jewish law) is not forbidden, but when he's doing it for you, it is forbidden.

Am I actually obligated to tell him simply to leave my car running in the street so that he won't desecrate the Sabbath for me? Meaning: even going to some parking spot for my sake is forbidden for him.
I'm asking how far my obligation goes that he not commit a transgression involving my property when it's not for his own sake.

You're not supposed to tell him anything. Give him the keys and let him do as he understands.

Can I tell him the code for the car?

Yes, that's no different from giving keys.

And what if he's traditional, like many of the people of Israel, and believes?

If he believes in the giving of the Torah, then he is subject to commandment observance and there is a prohibition against causing him to stumble. But there is also a prohibition against blocking him, and the decision is his whether to drive himself and therefore move your car. So in my opinion it is still permitted. The decision is his and not yours.

With a traditional person, seemingly this could be a problem, because it's a kind of "two sides of the river," since he won't be able to drive without my help in giving the key. No?

And if I remember correctly, there are medieval authorities who forbid it even when it's not literally "two sides of the river" (meaning that he could commit the transgression even without help), so anyway it's problematic.

Of course I'm talking about an unintentional transgressor and all that comes with it, because with an intentional transgressor there's no question at all—help him up and all the slogans.

First of all, the discussion here is about an intentional transgressor, not an unintentional one. Second, indeed there are medieval authorities who define in a "one side of the river" case a rabbinic prohibition of assisting. And third, even given all that, as I wrote, if you blocked him you cannot prevent him from driving, and therefore it is permitted to give him the key.

The artificial intelligence's answer.

Hello,

First, it is important to apologize to the person whose car you blocked. Driving on the Sabbath is a serious religious prohibition, and it is important to show understanding and concern for his feelings.

Regarding the halakhic question, there are two main principles we need to consider:

1. The prohibition of "do not place a stumbling block": it is forbidden to cause another person to commit a transgression. In this case, if you give him the keys, you may cause him to drive on the Sabbath, and thereby commit a transgression.

2. "Indirect causation": a person is not responsible for another person's actions. In this case, it can be argued that you are not responsible if the person decides to drive on the Sabbath, since he is an adult who can make his own decisions.

The Jewish law

Jewish law rules that it is forbidden to give car keys to another person on the Sabbath, even if he requests them, because this is considered "do not place a stumbling block."

However, there are exceptional cases in which this may be permitted, such as:

If the person is in danger
If there is an essential need to travel (for example, to save a life)
If there is concern that the person will cause greater damage if he does not receive the keys (for example, if he tries to break into the car)
Recommendation

In this case, my recommendation is not to give the person the keys.

Alternative options

Offer him an alternative: a taxi, a ride, or walking.
Explain the situation to him: tell him that you keep the Sabbath and cannot give him the keys, but that you are sorry for the inconvenience.
Offer him help: if there is another way you can help him get out of the situation, offer your help.
It is important to remember that even if you cannot give him the keys, you must treat him with respect and concern.