A few weeks back, I was running errands in my car when I caught the end of a program on KUOW-FM that I wished I had heard in full. So before driving to my next stop, I navigated to the Seattle public radio station's website on my iPhone, searched for the segment archive and streamed the MP3 over the 3G connection as I drove around, playing the audio from the phone through my car stereo via the auxiliary jack.

In hindsight, I probably could have gone through the on-demand local programming section of the NPR News iPhone app instead, but I didn't happen to think about that.

At any rate, it felt like a cool workaround, much more flexible and real-time than downloading a podcast in advance. But based on some new audience trends disclosed by NPR today, it looks like I'm not alone in starting to use my phone in my car to create, on the fly, a more customized experience than possible through the traditional car radio.

This blog post from NPR describes its hour-by-hour audience across its various platforms -- radio, the web, and its mobile phone applications. Here's what stood out to me, based on my recent experience.

As for mobile platforms, the NPR News iPhone app has a slight bump in traffic in the mid-morning and evens out throughout the day. Curiously, this is a unique pattern among NPR mobile platforms, and may indicate a strong use of that particular app during the morning commute. (How much of that use is taking place in cars is not something we have a strong sense of yet. The latest "Infinite Dial" research (.pdf) indicates that 6% of American cell phone owners have streamed audio through their phone to their car stereo.) The Android app, iPad app and mobile website all see more steady use throughout the day until late evening, when the mobile site and iPad app experience a bit of a second wind of traffic, perhaps as people get their last dose of news before bed.

Presumably a good chunk of that morning-commute usage is coming on buses and trains. But as evidenced by the Infinite Dial study, some of it is no doubt happening in cars, as well. It should be particularly interesting to see what happens as technology and usage patterns evolve.

To me, the mobile phone actually seems like a stopgap. Maybe this already exists, but I'd personally be more interested in a car stereo with built-in mobile wireless that could install (and stream audio from) third-party apps. The iStereo?

Hat tip to PaidContent for the pointer to the NPR report.