so after owning my vectra 1.9 cdti 150 for about 4 years, these are the problems i've had.....

Replaced...
Alternator, aux belt & tensioner
Inlet manifold
Egr
Glow plugs
Boost sensor
Thermostat
Cambelt, tensioner, idler, water pump
Injector seal x 1
Injector plugs x 4
Blower resisitor pack thermo fuse & heater recirc servo
Clutch/ Slave/ DMF/ & Crank oil seal
Clutch pedal return spring
Suspension springs x4
Drop links
Front arb bushes
Rear hubs
Rear upper control arms
Rear hub carrier lower bushes
Sump plug

also...
drivers side mirror fell off
mould in bottom parts of tail lights
headligts top part of plastic clouded over
cruise control stalk intermittent - cleaned out contacts
brake pipes under car gone rusty - wire brushed back and treated with rust killer

all seem to be common problems .....