Different “sizes” of Mercedes-Benz E-Class Cabriolet.
Road tax, as its very term suggests, is a charge levied on your usage of asphalt (whose science is explained here). Yet the authorities continue to calculate said tax based on the car’s engine capacity. What does the internal combustion volume of the powerplant have to do with the road space used by the vehicle proper? It’s the undercarriage that actually occupies precious room on the tarmac!
In the past, cars with bigger engines inside were also bigger on the outside, but these days, this assumption is less valid. We have 2-litre pocket rockets (such as Volkswagen’s Golf GTIs), a current Civic that is larger and heavier than a classic Accord, and compact saloons with colossal power.
Take the previous Mercedes-Benz C63 AMG, for example. It’s a handy 6.2-litre hot-rod which attracts over three times the annual road tax of the old 3-litre S300, even though the crazy C-Class doesn’t take up three times more bitumen than the S-Class. In fact, the long-wheelbase limousine requires around 15 percent more driving/parking space than the C63, so if anything, the flagship should be taxed more heavily for occupying more of the street/carpark.
Estimating the amount of road space taken up by a vehicle is easy: its length multipled by its width. Imagine a sheet of steel on wheels. Simplistic, yes, but it works well enough in my books – certainly better than the convoluted formula employed by the authorities to compute your car’s annual road tax.
I hereby suggest a simpler and fairer formula to determine your ride’s road tax: length times width (both in metres) times engine capacity (in litres) times 100. I’m no mathematician, but calculating road tax this way seems to be more equitable than the current system, which is more like an engine levy.
Engines by themselves do not contribute to traffic congestion; it’s the cars they power that clog up the roads.
Small, smaller, medium, large, larger and largest.
