Just got back from a trip to Spain by road in my 2001 hdi 16v 806. Done 3300 miles and averaged 45mpg. A curious problem we had on the way down and partly on the way back was that the car was very slow up the steep hills of southern France and northern Spain. The car would lose speed rapidly and even had me in 2 parts in 2nd gear doing less than 20 mph (and getting ready to dig out green flags number, or the undertakers). Going through the gears the car didn't seem to be too slow but didn't want to pull over 3000 rpm coming down the box the car had nothing at all, the proverbial rice pudding had nothing to worry about. After a fraught time at a peage on the return leg involving a very bewildered Frenchman. I rather became a boy racer and booted the old girl a little, the next hill she went up like a scalded cat and most of the way home she behaved almost flawlessly but still every now and again shook her head and wouldn't go. There was never any warning lights appeared on the dash at any time. She had a good service before she left had a sensor changed the week before we left. Sorry it's long winded but the symptoms where weird, does anyone know what maybe causing this as apart from the hills she was spot on.