I’ve got the Rover 75 variant and am well happy with the last 5 years of ownership.The engine is from the pre 2000 BMW 320 diesel
Main things on the 75/ZT diesel are ,
MAF sensor – these go out of spec after about 50k and the engine can start overfueling (more a problem in summer than winter) the original Bosch one can be replaced with a Pierburgh one with a compensator box .have a look on http://tuning-diesels.com/75Zt/R75serv.htm#b .
Slave cylinder – as it’s inside the clutch housing it’s an expensive fix . In fact anything to do with the clutch on these engines is a bit pricey , my replacement clutch/slave and master cost me £500.
Rear coil springs – on the tourer models especially they have a nasty habit of breaking near the bottom of the coil and unless you remove the wheels you can’t tell.
There have been some reports of front coils breaking and a lot of cars were recalled to have a plastic tyre saver fitted around the lower half of the coil in case of snappage.
That really is about it , I get 42mpg on combined journeys >120 miles max but tickling the throttle fully loaded on a run I’ve had nearly 55mpg. As for spares there’s plenty about , a lot of the parts are straight out of BMW’s parts bin.
Have a look on here http://forums.mg-rover.org/forumdisplay.php?f=90