I dont. I have a difficult time placing a gender on inanimate objects.
I have this theory that the reason English-speaking peoples (Brits, Merkans) have been de facto rulers of the world for the past few hundred years is because our language does not have gender on everything. People that speak these other languages have to always keep gender in mind when conjugating and forming sentences, gender that is often applied for no good reason (a pencil is masculine but a notebook is feminine - WTF?). Sure, as these other peoples - furiners, lets call them - grow up, they learn what things are feminine and masculine and it becomes a matter of memorization, but those microseconds of effort spent recalling whether or not to use masculine or feminine pronouns and conjugations, etc. add up. All that extra effort but forth on word gender by these furiners could have instead been put into becoming better at the colonization, exploitation, and subjugation - just plain winning, really - that we English-speaking people have mastered. I cant prove this theory, but I feel its accurate.
So, having said that, I feel that were I to start referring to vehicles in the feminine (or masculine, for that matter) then I am no better than some beret-wearing Parisian sitting at cafe muttering about stupid Americans while nibbling a croissant. I envy him his croissant (best pastry, hands down), but not his gender-based language.