Last year, as the understanding of how smartphones are changing our lives really hit home, a realization surfaced: They're replacing the personal automobile, both as a vehicle for consumer identity and as a tool for accomplishing everyday tasks. That's why there's such a fierce war between the makers of the software systems that power those phones, Apple and Google, which want to capture as much of our attention as possible. The character-defining question of our time isn't "are you a Chevy person or a Ford person," it's "are you an Android person or an iPhone person?"

Well, cars have evolved. They're now basically smartphones on wheels -- and are starting to align themselves with one side or the other.

The upcoming Consumer Electronics Show, an annual gadget fiesta in Las Vegas, has become a battleground. In advance, Audi has announced its new alliance with Google, which will bring Android-compatible operating systems into many of its new vehicles. That's a response to Apple, which has already recruited BMW, Mercedes Benz, General Motors and Honda. "With its 'iOS in the Car' initiative announced last June, Apple hopes to turn the iPhone into a kind of brain for operating dashboard electronics, using the car's built-in display to interact with services such as maps and traffic information," as the Wall Street Journal put it this morning. Google, in turn, will "allow drivers and passengers to access music, navigation, apps and services that are similar to those widely available now on Android-powered smartphones."

Is it a car? Or a phone? (Apple)

It's probably an asset to have your car integrate with the device that runs the rest of your life. The annoying part comes in when you think about the implications of cars getting enmeshed in the platform wars: If you want an Audi, and you have an iPhone, will you have to switch to an Android in order to get the most out of your driving experience? A couple weeks ago, Google hinted to EE Times that its announcement would include the formation of an industry consortium that will create compatibility standards to ease the process of making apps for cars -- but will they just be for those that run Android? Developers already have to make a version for each operating system on regular phones; now the inconvenience could extend  into the auto world as well. (And considering the way internet companies form alliances with phonemakers now, an Amazon car or a Facebook car could be next.)

It would seem logical for a car company to stay platform-agnostic, so as not to repel consumers who are wedded to one operating system or the other. Hyundai, for example, is developing near-field communications technology that turns any kind of phone into a key fob. But big corporate alliances tend not to work that way: It's very difficult to serve both Coke and Pepsi as a fast food restaurant, for example, because of the marketing and bulk purchasing advantages that come with signing on exclusively with one or the other.

So, let the division of the driving world begin.