There seems to be some unintended irony in the naming. There was a popular sedan car Moskvitch [1] (masculine for Moscow resident), and Zaporozhets [2] (masc. for resident of Zaporizhia in Russian). Both of these cities had resp. car factories. However, Kharkiv, had none, instead it had a tractor and tank factory... The product is literally out of the league, so is the name Kharkovchanka (fem. for resident of Kharkiv in Russian)
I'd guess the choice of masculine for a car name is in line with masc. for 'automobile' in Russian. Meanwhile, the feminine in this case is, perhaps, for fem. 'machine' in Russian. Just a guess.