However, should customers embrace the playback capabilities that marginal component costs will soon make a standard feature of their handsets, Apple will need to take a more active role if it wants to preserve the portable digital music experience it has executed so well.

ENGADGET: Switched On: Why Motorola's ROKR plays the humdrum

But having transplanted the heaviest and most costly component to the c, you'd wind up with only marginal improvements in cost and fuel economy, and a smaller, crummier car to put them in.

WSJ: 2012 Toyota Prius c Review: Pleasure Not Included | Rumble Seat by Dan Neil