Seat, Volkswagen and Audi have revised CO2 figures upwards on a number of models across their ranges.
A report by Autocar has shown that a number of vehicles have seen changes to posted emissions figures, with revisions of up to 10g/km in one case.
The most significant change is to the emissions of the automatic Seat Leon X-Perience 4x4 estate model - at launch, emissions were 129g/km, and have since increased to 139g/km. The increase means a two percentage point increase in benefit-in-kind tax for drivers, as well as the loss for businesses of the 18% write-down allowance, because emissions are above 130g/km. The manual car emissions remain below 130g/km, at 125g/km.
A range of Audi models, including the A1 and certain variants of the new A4 have seen increases of 2-4g/km, with the majority adding an extra percentage point onto a driver's benefit-in-kind tax bill.
And today (Thursday), figures for three of the six Volkswagen models affected in the UK have been released, with revisions affecting 2.0-litre 150ps diesel manual Golfs, rising from 106 to 109, and 109 to 112g/km dependent on trim. One Jetta and one Golf cabrio model are also affected, with the cabrio seeing a 6g/km rise.
Volkswagen says less than 100 fleet vehicles on order but not yet delivered have been affected, and customers have been offered the option to accept the changes, cancel the order or swap to another Volkswagen vehicle without penalty.
An Audi statement said: "Throughout the year the CO2 emissions of our vehicles are regularly checked because small changes do occur in terms of production processes, equipment levels, etc.
"When these changes create a subsequent change in the CO2 emission levels of a vehicle, this is discussed with the relevant authorities and a new official figure is determined which becomes the new official figure for the brochure."
An Audi spokesman told Fleet News that figures for the A4 were adjusted as part of the vehicle launch cycle.
He explained: "Data for the 218PS V6 TDI quattro, classified as provisional in our customer-facing price and spec guide was then confirmed before production started with slightly higher values. This isn’t an uncommon occurrence.
"As the revised figures were made available before start of production, customers who placed an order based on the preliminary data in the pre-sales phase were informed of the changes and were able to amend or cancel their orders.
"In cases like these, we block all orders until customers have notified us about their final decision."
Cars previously registered with the lower CO2 figures will not be affected by the move.