I had a 2001 406 HDi and it was certainly a memorable car. Mostly because of the constant electrical faults, trim creaks, hopeless dealer backup and the fact a UKP 2000 part on the fuel system died with the car 6 weeks out of warranty and Peugeot wouldn't even contribute to the cost.
In its defence, it was comfy and refined though, and it handled well. But give me a Mondeo any day. The two I've had since have been near faultless.
I bought a 2006 1.8 platinum putting out 125 bhp. A month after I got the car I had to leave in for gear selector lever. I have the odd hard start where it takes a second crank to get it going. Other than that, car runs pretty darn well.
You are all probably not aware that the Ford TDCI and the Peugeot HDI engines are almost identical, except from smaller changes to the injection system. Talking that "one is better than the other" is meaningless.
The are both variants of the DW10 engine, which is a PSA Diesel used by Peugeot, Citroen, Ford, Volvo, Jaguar, Land Rover and Mazda (some more?).
I bought an 2006 1.8 Platinum. It was the best value for money car I ever bought... 7500 Euros for a 3yr old 40000Km car (original price high 20s) It still even has a hint of the 'new car smell'.
It drives smooth. It is big quiet and comfortable and feels solid. 36 / 38 mpg, whilst not great, is acceptable. Climate control, cruise control, nice alloys, very good interior finish and trim...
Huge space in both cabin and boot (hatch type). This is my second Mondeo... If it proves as reliable as the last one, I would almost go again for a Mondeo in three years time (but then I will need to research and evaluate the new model).