How much thought do you put into your character's mode of transportation? If your hero or heroine lives in New York City, then the metro would make perfect sense...or maybe even a limosine or a taxi. Each one of those choices would paint a completely different picture of your character's character.
What if your main character owns a car or truck? Vehicles have character, and their character needs to match that of your hero or heroine. Got an alpha hero or heroine? Beta? You'd better believe there are alpha and beta vehicles out there. Cars have long reflected economic status, social status, and personality. Ownership could reflect anything from hobby and personal taste, to need. You know that single father hero with five kids? I see a stationwagon or minivan in the picture. The european billionaire? A Maserati, perhaps.
You get the idea. In Just Breathe by Susan Wiggs, her heroine discovers her husband with another woman. She'd spent her marriage adapting to who he was and trying to make him happy. When she leaves him, one of the first things she does is trade in his GTO for a little, blue Mini Cooper. It was her way of saying 'screw you', I'm driving something that reflects who I am.
Linda Lael Miller's Texas McKettricks keep their expensive sports cars in a garage as big as the average house, but when they're truly in their element, they ride their horses...or their women. And man are they great riders -- I mean drivers -- Uh, back to cars.
I have one manuscript where it was important for the heroine to drive a hybrid car. In another manuscript, there's a distinct difference in what the hero and heroine drive. He's a small town firefighter in a big-ass, American truck, and she's perpetually moving from city to city, hence a fuel efficient, Japanese compact.
So what do your characters drive? Is your character's car big or small? Dirty or sparkling clean? Falling apart, vintage, or brand new? What do different vehicles represent to you in terms of character?