What It Is: Picnics and beach parties could get a lot more memorable with new sound systems that let tailgaters tap their inner DJs. Auto makers are equipping some vehicles with souped-up cargo-area speakers and audio controls that allow for back-door song adjustments.

How to Get It: The 2007 Jeep Patriot and 2007 Dodge Caliber offer optional speakers that fold down from the liftgate when it's open; the speakers look like a mini-boom box hanging from the back door.

GMC's 2008 Acadia SLT1 and SLT2 come standard with rear-cargo area audio controls; two of the Acadia's 10 Bose 5.1 surround-sound speakers and an amplifier are located in the rear tailgate.

The Nissan 2008 Armada's Bose audio system includes third-row and rear-door speakers as well as third-row auxiliary audio inputs so that the MP3 player of choice can sit a little closer to the party.

The 2007 Pontiac Torrent's hatchback door was designed to move sound forward when closed and focus outward when open; Pontiac said the little car could function as "one big resonator." The Torrent also offers a rear-cargo storage shelf that's attached to the back of the second-row seats but swings out to form an impromptu picnic table.

Upside: Most of the sound systems have real power behind them so playing music from the car is likely more effective than a boombox on a picnic table.

Downside: What might be music to you could irritate others within earshot who weren't invited.

Cost: Flip-down liftgate speakers are $495 in both the Patriot and the Caliber, as part of a premium 458-watt Boston Acoustics sound-system package. The Bose audio speaker with rear-panel controls comes standard on the Acadia SLT1 and SLT2 but isn't available on the base Acadia model. The Bose audio system is standard on the 2008 Armada LE and is a $2,500 option for the 2008 Armada SE. Cargo-area speakers are part of the Torrent's standard design; the fold-out picnic-table option is $160.