"Eight boats and two cars."
Translation:Ochd bàtaichean agus dà chàr.
Adding to tj4234’s reply: if you want to know the historical reason – because Gaelic had a separate dual forms of nouns that came after dà. But the dual forms of most nouns were similar or identical to singular forms and after a while they completely merged with singular. So today singular is used after dà instead of older dual and plural has never been used when counting two things.
Similarly in Russian genitive singular is used after два, because older Slavic dual of most nouns sounded like genitive sg. and thus the dual merged with gen.sg.
In Irish, too, singular is used after dhá, but in dialects where separate dative forms exist, the dative sg. is used, because dual merged with dative sg. there, so eg. dhá láimh (two hands, instead of
dhá lámh or dhá lámha).