Does that mean that diesel cars are being penalised?
No. Diesel cars emit less CO2 than petrol cars and so would be taxed on a lower percentage of the car ‘s price if the charge was based purely on CO2 emissions. So without any adjustment they would have a tax advantage over petrol cars. But this tax advantage wouldn ‘t be justified as diesel cars emit more local air pollutants than petrol cars. So the aim of the supplement is simply to ensure that the new system doesn ‘t end up damaging local air quality because there is an in-built advantage for diesel cars.
