Ben - You're killin me... LOL. I was hoping to get an answer closer to "yeah, something like that..." I guess it's back to the webpages for me!
Matt - 1hz would be annoying, yes. But, I doubt it would "shake your car to death", simply b/c the controller just couldn't generate a frequency that low strong enough to shake much of anything, especially w/o destroying itself first.
If you could manage to get it to work that low - without killing itself - you could just rubber mount the controller and take care of that vibration. You can't hear (on average) below 20hz anyway, so you'd be in quiet while you were driving, and 1hz has a backfrequency most of the time that blocks resonance in the air as well.
Get a sound program and play 1hz on your speakers in a quiet room as loud as you dare... you'll hear a "whoosh" noise every second. If you do this in a room that has normal ambient noise, you'll lose the "whoosh" noise along with some other sound you should probably normally hear.