Suspension

Stop the wheels flopping from side to side on cornering. A Capri is a good example of how unstable the back end can feel under cornering without them.

simple really cars are designed with safety in mind, so they understeer on the limit when you lift off the front end steps back into line and away you go cars like the 306 (for example only) which have a rear beam means that the wheels don't bend to the pitch and angle of the road sp when you get a sudden shift in weight the back end isn't as glued to the road as you would think and you follow the understeer with a beautiful, if slightly expensive, pirouette at leas, that's the way that everything seem to me

Nom waffled on in a quite bewildering manner to produce...

yup, 306 has passive rear wheel steer due to the design and the use of compliance bushes mounting the rear axle set up. Handles rather well if you ask me.

The reason cars tend to use MacPherson struts is because they're relatively small, and they're very simple and cheap.

The reason why new FWD cars have started to use complex multi link read suspension set ups is because the trick with getting a front wheel drive car to handle is generally trying to get the back to handle as badly as the front does. Using a complex multilink set up at the back and struts at the front mean it's easier to make the car handle more faithfully whilst still keeping some sort of ride quality. Therefore keeping a nice balance in the handling along with a decent ride quality.

Much cheaper using torsion bars at the back if you ask me. 205 GTi's seemed to handle well enough with them..