Toyota sales fell 17.8% in December
Japanese vehicle sales had their worst December on record, with demand plunging 22% compared with the same month of 2007.
December sales of cars trucks and buses fell to 183,549, according to the Japan Automobile Dealers Association (JADA).
Japan's recession has been blamed for the fall, together with the trend of people moving to urban areas and relying on public transport.
Vehicle sales for the whole of 2008 fell 5.1% to 5.08 million.
It was the fifth consecutive year of falls, taking sales down to a 34-year low.
JADA predicted last month that sales in 2009 would fall to 4.86 million, but there is concern that the figure could be even worse than that.
"We never imagined sales would fall this badly," said Takeshi Fushimi, director of JADA.
Lack of financing has been less of a problem than it has elsewhere, according to JADA.
In the US, a major factor behind the slump in car sales has been people being unable to take out car loans.