Q. What is wrong with going in a car on Shabbat?
A. Shabbat is the Jewish time-out period when we withdraw from the pace and pressure of the outside world. One day a week we return to the Garden of Eden. We push aside our concerns about buying and selling, moving person and property from place to place, changing and exploiting the world. We concentrate on our souls, hearts and minds, ourselves and our families. Utilising transport, especially driving a car, symbolises activities which have no place in our Shabbat existence.
From the halachic standpoint, pressing the accelerator of a car releases fuel into the combustion chamber of the engine where it is ignited, thereby transgressing the Biblical prohibition of Mavir, kindling a fire on Shabbat.
There are circumstances in which, technically, certain modes of transport could theoretically be utilised on Shabbat, but they mostly entail mar’it ayin, giving other people the wrong impression, and in conceptual terms they don’t fit into the Shabbat mode. However, with regard to travel by ship, if you embark before Shabbat and most passengers are not Jewish, the t’chum Shabbat (the Sabbath limit of 2000 cubits – 0.94 km or 1.16 km depending on your definition) does not apply to travel by sea.