The latest misery came despite a fall in the cost of oil, although there was a small cut in petrol prices.
Diesel pump prices went up by 1.6p north of the Border over last month to average 141.6p a litre, according to the latest Automobile Association fuel price report.
That compares with an increase of 1.3p across the UK to an average of 140.95p.
Petrol prices in Scotland fell by 0.6p to 133.4p, compared with an average cut across the UK of 0.81p to 133.7p.
The AA said diesel prices traditionally increased at this time of year because of rising demand for heating oil.
However, it warned that the growing disparity between diesel and petrol meant drivers who had opted for more expensive diesel engines for their better fuel economy would find it harder to recoup the extra cost. The survey showed that the price gap between the two fuels – which has reached 8.2p a litre in Scotland – had never been bigger other than during the major price increases in 2008.
The AA said that despite the petrol price fall, it had yet to reflect the full drop in European wholesale prices, of some 50p a litre two months ago to about 45p now.
AA president Edmund King said: “The fall in the price of oil due to the eurozone crisis had brought some hope of respite for drivers, but the opposite has happened for diesel car owners.
“The petrol price may have been falling overall, but it’s dropped faster for some than others, and that adds to the frustration.”
Institute of Advanced Motorists chief executive Simon Best said: “Throughout much of Europe, there are lower duty rates for diesel than petrol that bring both fuels to a similar price.
“In the UK, petrol and diesel have the same duty rates, so the pump price reflects their wholesale price difference.
“Demand for diesel generally rises in the autumn because heating oil is more or less the same product. This pushes wholesale prices up, which is reflected in the pump price. We urge fuel retailers to cut both petrol and diesel prices as quickly as the wholesale prices fall.
“The government should not subsidise diesel users by charging a lower duty rate. Diesel cars still achieve more miles per gallon than similar petrol versions.”
Association of British Drivers spokesman Brian Macdowall said: “Whilst there is a problem with fuel supplies, profit margins and speculators, petroleum is essentially a cheap product.
“Tax, however, adds around 80 per cent to the price per litre, making this essential product cripplingly expensive, and at current prices, is damaging the economy.
“We continue to call for a sliding-scale fuel duty based on a percentage which falls as oil prices rise and increases when they drop, in order to stabilise the cost of motor fuel at around £1 per litre.”