This ad was just running on the TV at the moment less then a minute ago, and I, too, was wondering about its origin. I really don't think it was written for Chevy (All commercials, these days, it seems, are using already written love songs and such to promote their products -- I think this is part of that tradition) If I start typing, I might remember it:

There is a place where I go, when I want to roam,
And nobody knows it but me.
The roads don't go there, and the signs all stay home
And nobody knows it but me.
It's far, far away, and way, way afar
Over the moon and the sea.
And wherever you go, that's where you are,
And nobody knows it but me.

Yay! I did remember it! (I think. Did I?)

So (assuming this was not written by a Chevy ad exec.) who did write this?

I've seen "Wherever you go, that's where you are" quoted several places (including the movie Buckaroo Bonzai, which came out over 20 years ago), which is one reason I'm assuming this is not something new that just came from the brain of an advertizing executive....