Abbreviation of ワンボックスカー. Refers to a boxy 6–8 seat vehicle with sliding doors, common in Japan.
wasei-eigo (Japanese-coined English), from one box
See also: ワンボックスカー
A minivan is convenient when going out with the family.
That minivan has sliding doors on both sides.
Wasei-eigo abbreviation of ワンボックスカー, from English 'one box' + 'car', referring to the single-box body shape.