Prescient Audio PATD12
For car use, it has the added benefit of reducing weight, presumably good for your shocks. For concert use, 10 of the drivers can fit into an iPhone-shaped panel, reducing the bulk of stage equipment while still letting you know how the bass player really feels. But the first available product is for home use: the PATD12 ($1,000). This thin-profile in-wall sub can fit between studs, with the 12-inch driver in an enclosure just 2.25 inches deep. See prescientaudio.com.