The plan will be implemented at the same time the country's sales tax rises to 10 percent from the current 8 percent, according to the sources, who insisted on anonymity because it has not been finalised.
The car plan is contained in a draft of the ruling bloc's annual tax code revision seen by Reuters.
The new measures should produce tax revenue of around 89 billion yen ($725 million) in the fiscal year ending in March 2018, about 21 billion yen lower than the current year's income from the car acquisition tax, they said.
The draft tax revision is expected to be endorsed on Thursday by the ruling Liberal Democratic Party and its coalition ally Komeito.