Right-hand-drive Volkswagen Polo diesels will have slightly worse fuel economy and higher CO2 emissions than the left-hand-drive versions sold in mainland Europe.
This is because the oxidation catalyst and diesel particulate filter in the exhaust system have been moved to allow the controls to be switched to the right side of the car.
The switch means that the 1.2-litre Polo Bluemotion, which has the lowest CO2 figure of any car on sale in Europe at 87g/km, can't make the same claim in the UK.
The Polo's emissions in the UK are 90g/km, while fuel economy dips from 85.6mpg to 83.1mpg.
The two 1.6-litre Polo diesels (74 and 89bhp) are also 3g/km worse off in right-hand-drive form, while the official fuel consumption figure falls from 67.3mpg to 65.7mpg.
Taxation remains unchanged
The good news is that both road tax and company car tax are unaffected by the right-hand-drive car's drop in efficiency it's not significant enough to move the Polos up a tax band.
Other VWs are not affected by the transformation from left- to right-hand drive because there is more underbonnet space to re-route the controls.