I have a new c-class estate - 320cdi. Less than 2k miles. Love the engine to bits - but after some short local trips reversed the car into the drive area to clouds of blue/grey smoke which smelled acrid. No warning lights and local dealer said today they could not find a problem. Reversing back on my return home, no smoke but strong acrid smell again which I could detect in the cabin while still reversing as well as when I got out. Any ideas appreciated.