I'd be downright embarrassed/ashamed if I returned a loaned car like that...
But I guess I'm one of those rare breeds who even treats rental cars better than my own. "If it ain't mine, treat it with respect"
You should see me drive Charlie's Porsche... I have 9 years of track experience, and yet I drive his Porsche like a granny. I respect him too much to beat on his car..