I would just add that none of my five SD1s ever had a water leak. It's common for the speedo transducers to go. The heat from the gearbox makes the insulation go brittle, so the wires break off the body of the transducer. In fact on my red Vitesse (see my other posting) it caused a short-circuit that almost set the car alight!
The central locking often gets a bit dodgy. Invariably after time you end up with a car in which only three out of four of the doors all lock/unlock at every key turn! It's happened on mostof my cars. All the minor electrical problems like this are manageable, albeit tiresome.
I've had three gearbox failures. That's always a problem. Every V8 I've had has also required a new camshaft.
Michael