A little video from a GM Grand Prix owner that discovered the results of a rusted out sub-frame while driving. A worthwhile video to watch:

Great video to share Michael, thanks for sharing it!
I think I may look my sub frame over ASAP, hopefully there is no rust, can't say the same for my floorboards though, the back ones are taking on water again when it rains, so back to chasing water leaks.

That is good info. Almost makes me want to go look at mine now...but gotta wait for the 1ft of snow to disappear.

I love living in California! The worst rust problem I've ever seen is a coworkers dodge caravan from Michigan rusted out the strut tower and tried to poke through the hood. It went straight to the junk yard, no fixing that one.

Yup good to look for rust but also to look closely around the sub frame bushings etc for cracks. See with a pry bar if you can move the frame in any directions, not good if u can.
Once a year make sure the bolts are also torqued tight.

A very informative video. I remember, some time ago, we had a forum member who had that happen to him and his 400k-mile 3800.

The GP'* seem to have a rusting problem. The local oil change place warned me that my frame was so rusty that they couldn't even jack up my car to rotate the tires. Funny thing is, the next month, it was in and out of the tire shop without so much as a peep.