On that day Mr Shetreet gets his ministry to issue him with a second - and less obviously ministerial - car, which allows him to travel without offending the religious public. He says the arrangement, revealed when the special Sabbath car was stolen last Saturday, shows he has a peculiar sense of delicacy. Other ministers simply put different licence plates on their vehicles.
"The Volvo is frozen [on Sabbath]," Mr Shetreet said. "It is parked and never driven." Normally he would use his family's but if they are using it then "I ask that another that is free be put at my service."
Admittedly Mr Shetreet has only been in the job two months, doubles as Minister of Economy and Planning and is not himself ultra-Orthodox. But an Israeli government ignores at its peril the sensitivities of those who are. In 1990 an influential ultra-Orthodox rabbi kept Labour out of office because, he said, he suspected people working on Labour-backed kibbutzim of eating rabbit, a forbidden animal under kosher rules.