Wednesday's (21 March) Budget introduced higher duties for more economical models than larger-engined vehicles, according to analysts Cap. The alignment of petrol vehicle excise duties with diesel now means an economical 50 mpg petrol Vauxhall Corsa 1.0 receives a tax increase of £5 more than an Audi A4 diesel 3.0 Quattro, which achieves 34 mpg and emits 66 per cent more CO2.

Cap said the media focus on Band G cars had distracted focus from the fact that the government was attempting to raise additional revenue from all drivers. Mark Norman, an analyst with Cap, said the new measures were the highest increases in road tax since 2002. “At a time when politicians are constantly emphasising the importance of reducing Britain's carbon footprint it seems ironic that the driver of a 50 mpg car will pay a greater increase than someone burning almost twice as much fuel,” Norman said.