Google (Nasdaq: GOOG) is putting its Android operating system to good use in smartphones today -- about 100,000 of them every day, to be precise. Next up, you'll see the same platform in tablet computers, and then powering TV sets and set-top boxes in your living room. So where does Google go from there?

According to Andy Rubin, Google's VP of mobile platforms, your car is Android's next target platform. In an interview with San Jose Mercury News, he said: "We're at about 4 billion cell phones. About 1.4 billion Internet connected PCs -- that includes desktop and laptops and everything else. Like 1.2 billion automobiles. Some 800 million TVs. And it's like, 'OK, let's target the top four.' Let's do everything we can to get the big ones." There's no word on exactly what Android might run inside your car, but it seems reasonable to attach it to in-car infotainment systems. The system already comes with navigation software, for starters.

Google's reasons for going after the largest markets available are very simple: a large audience translates into more advertising clicks. Profit follows naturally, like pastrami on rye.

It's a very different model than Apple's (Nasdaq: AAPL). Apple likes to sell hardware and make direct profits that way, then add to the profit pile with associated software and media sales in closed, symbiotic systems. Google gives its software away and hardly cares about retail sales; the real dough rises from hordes of Internet-connected consumers with itchy ad-clicking fingers.

That's exactly why Rubin's budget "isn't based on sales." Instead, it's all about "more eyeballs, more happy, delighted users, more face time. You carry your cell phone around eight or 10 hours a day, the revenue crank just turns." Google is kind of like ExxonMobil (NYSE: XOM) in that regard; drive a Ford (NYSE: F) or drive a Toyota if you prefer; either way, you still need gas in the tank. Motorola (NYSE: MOT) and HTC are the auto makers in this parable; Google runs the richest oilfields in the business, despite the best efforts by Yahoo! and Microsoft (Nasdaq: MSFT) to steal search and advertising business from Big G. All roads in cyberspace lead to Mountain View.

It all makes sense, doesn't it? I'm a happy long-term Google owner, because the business just follows from keeping users satisfied. Discuss this automatic cash machine in the comments below.

Fool contributor Anders Bylund owns shares in Google, but he holds no other position in any of the companies discussed here. Microsoft is a Motley Fool Inside Value selection. Google is a Motley Fool Rule Breakers recommendation. Apple and Ford Motor are Motley Fool Stock Advisor selections. Motley Fool Options has recommended a diagonal call position on Microsoft. Try any of our Foolish newsletters today, free for 30 days. You can check out Anders' holdings and a concise bio if you like, and The Motley Fool is investors writing for investors.