My S1 Roadster didn't have an anti-tramp bar. OK, you can drive it like that, but when accelerating sportily, the cardan shaft lifted and touched the rear underbody, which made a loud grinding noise. The S2 and S3 had an ATB. I had a second ATB fitted to the S3 and everything felt much more controlled. I even had a retrofitted Panhard bar removed because it added other unpleasant characteristics to the driving experience for my taste. But with two ATBs fitted I no longer needed it for cornering control.
