Hmmm never had a diesel truck but ran diesel powered cars for about 12 years. Both were Citroen's BX Model the last was a 93 and I would still be driving it except for a nurd in a white van wrote it off for me

now I have a Cherokee 4.0. Anyway if a diesel smokes on anything but very hard acceleration of a very cold start up the injectors need looking at. I put injection cleaner through it (added to the tank) about twice a year, changed the oil every 6,000 miles however I only changed the fuel filter a couple of times in the 9 years I ran the car. The 1.7L turbo diesel returned around 55mpg on average (imperial gallon = 4.54litres).
I think diesel is dearer because diesel engines are more efficient and the oil companies have increased the price so they don't lose out as until they got popular here it was always cheaper but once more diesel powered cars were on the roads it crept up past petrol. It's pure greed nothing more

.