This would be an optional extra that works in conjunction with your car stereo and suspension. An onboard computer would detect the rythm of the music you are listening to, and then searching through its current database of music it would find a similar song to what you are listening to. It will then send a signal to the car's suspension that would tell the car how to transmit the bumps and other irregularities in the roads surface through the vehicle. This movement would be co-ordinated so as to make the occupants of the car to bounce along to the music in the style that the car has deemed most appropriate. Obviously the system can be turned off for when you don't want to be 'dancing', and regular ugrades could be downloaded from the net containing the right suspension transmission pattern for all your favourite songs.-- kaz, Dec 23 2001 Lowrider hydraulic systems http://www.dynastyonline.com/lohi.htmHydraulic suspensions easily capable of the motion you describe (and then some). [bristolz, Dec 23 2001, last modified Oct 21 2004] Tempo Controlled Suspensions http://www.lowmoves.com/index.htm"Low Moves Rhythm Controller for lowrider air and hydraulic systems." [[wbi]'s link] [bristolz, Apr 23 2002, last modified Oct 21 2004] Beat detection is baked - just use that. And (fast) pneumatic shocks.-- phoenix, Dec 23 2001 nice, the system could also control an underlighter to change colours to the beat.-- notripe, Dec 23 2001 i want one-- edski, Dec 24 2001 at [admin: URL moved to 'link'. --bristolz] you will find something to this effect. The control unit is used for hydraulic or air suspension, but can be set to sequence or for an extra cost a music interface module will be added.-- wbi, Apr 23 2002 random, halfbakery