Sales of new vehicles fell 9.1 percent in July from the previous year to 317,928 units, the lowest level for a July since 1974, an industry body said Tuesday.
The figure, which excludes minivehicles with engines of 660cc and under, represents the 13th straight month of decline, the Japan Automobile Dealers Association said.
Industry analysts said consumers are choosing to buy fuel-efficient minicars to replace their larger vehicles because of rising gasoline prices.
The July sales fall was led by an 11.4 percent decline in car sales to 267,772 units.
Sales of small cars with engines of 661cc to 2,000cc fell 14.3 percent to 163,841 units. Sales of larger cars dropped 6.5 percent to 103,931 units.
However, truck sales rose 5.7 percent to 48,737 units for the 16th straight month of growth, while sales of buses fell 6.6 percent to 1,419 units.
Domestic sales decreased at four of the five big firms, with Honda Motor Co. the hardest hit.
Honda saw its sales plunged 22.8 percent to 33,436 units, and sales at Nissan Motor Co. took a 20.2 percent dive to 56,280 units. Sales fell 15.3 percent to 18,294 units at Mazda Motor Corp. and 3.4 percent to 144,733 units for Toyota Motor Corp.'s Toyota-brand cars.
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