My work has just bought an N reg astra turbo diesel estate which has running problems.
First start up is fine, runs well and is a little smokey but when it gets warm it missfires then goes to full throttle and beltches out blue/white smoke while making a loud knocking noise from the bottom of the engine.
The only way to 'shut down' the engine is to konk it, as when we try to turn it off at the key it keeps going.
The car has covered 120,000 miles and my boss bought it for 200 quid!!