differences between the 45 and the zs?

[TjP]

The ZS is a major improvement on the 45 in terms of handling, which I think is mostly down to the suspension.

A few bits:

Suspension and Steering

Low ride height
Sports springs and dampers
Front and rear anti-roll bars
Sports tuned power steering
Quick ratio steering rack

Brakes

ABS with EBD (Electronic Brakeforce Distribution)
Ventilated front disc brakes (on 120, 115 TD and 180 models) and solid rear
Front disc brakes and rear drum brakes (on 110 and TD models)
282mm front/260mm rear discs (ZS180)

Edit: Above info was nabbed from a well known MG site, btw