About the only mass produced cars I know of which were designed with negative castor were the big Buicks of the early '60s, and all of us old codgers know how badly they handled (unless you belong to the Ralph Nader school of thought: that good handling consists of the tendency of a car to continue in a straight line, no matter what). When I converted my first series Mustang to GT-350 alignment specs for autocrosses, besides lowering the chassis mount point of the upper A-arm by an inch, I went from 1/2 degree positive to 4 degrees positive castor, along with a little negative camber, and it sure helped turn-in and front end grip, but it made the non power steering car a bear to park.