Here is an article about the halachic ramifications of autonomous cars. Among other issues, the author explores the possibility of riding such cars on Shabbos since they require no melacha on the part of the human being.
Then in the next issue Rav Yaakov Ariel Shlita [the Chief Rabbi of Ramat Gan] goes ballistic [I mean that in the most complimentary way] and says that the topic of using such a car on Shabbos should not even be discussed. It is חילול שבת מדאורייתא. The author then responds and seems to retreat from his position and asks Rav Ariel what he thinks about doctors and nurses using it for Pikuach Nefesh to get to the hospital. Then a very good friend of mine [whose real Hebrew name is not "מייקל" but "אהרן משולם"] writes the author a huge yashar koach on his article.
My own sympathies are ..... you guessed it [or did you] - with Rav Ariel!!! How would Shabbos look if everybody was driving around? And once it is a driving day, I believe that psychological mechanisms would be at play to convince people that other activities which they once assumed were forbidden are really permitted. Then goodbye Shabbos, חס ושלום! And even if that doesn't happen, the זילותא דשבת would seem to be egregious.
In general, many [not all] poskim disqualify many of the "grama" gadgets and contraptions on both halachic and hashkafic grounds. As Rav Asher Weiss Shlita concludes this article:
על כן קורא אני אל נא אחיי תרעו, כלך לכם מדרך זו כי לא זו הדרך ולא זו העיר. שבו ונוחו ביום השבת ועל מנוחתה יקדישו את שמך.
אלה הדברים היוצאים מנהמת לבי, מלבד מה שכבר כתבתי את הנלענ"ד שיש בזה חשש מלאכה דאורייתא.
