i'd have to agree with that...even in a crown, which most think is a heavy car...it's not really. 1300kg!! or thereabouts and i'm talking 1968/69 model. The rear spring rates are terrible. once you've got a full tank of fuel and a bit of weight in the back it corners and handles a whole lot better...just a bit underpowered to make it work better though.
i found softer springs with koni adjustables fixed it up...also added a second top control arm to my crown and dumped the panhard rod in favour of a watts link.
cheers struan.