Vehicle weights - What's the difference?

On its debut in Australia, Alfa Romeo's 4C sports car arrived weighing over a tonne, despite the factory's original claims it would sneak in under that threshold. There were various reasons for the lithe sports car packing on those extra kilos, but the primary reason was the factory's starting point was a 'dry weight'.

Weight might not necessarily be the first thing which comes to mind when we’re choosing a new car, but it does bear an influence on many factors. A vehicle's performance, fuel consumption, and handling are all significantly affected by how heavy it is. These days, car enthusiasts will cite weight as a factor equally important as engine output, gearing or traction.

Information on a car's weight is pretty easy to come across. Manufacturer brochures and websites sometimes provide the numbers; otherwise they can be found on the compliance label or build plate, or in the owner's handbook residing in the glovebox.

Take a closer look and you’ll see there are several acronyms, terms and standards used which can sometimes cause confusion. Let’s try to make sense of the basics of weight.

The weight of a vehicle changes depending on the condition in which it’s being used. How much fuel is in the tank? How many passengers are on board? Is the boot full of luggage? In fact, the numerous different weights we come across are determined by what condition is required by the particular measurement or standard.

'Dry Weight' is the lightest that a vehicle can be. The vehicle is measured without a driver, passengers or any luggage. The word ‘dry’ refers to the fact it is also empty of all fluids: fuel, oil, coolant and anything else. Of course this weight is significantly less than the weight of a vehicle in a driveable condition and therefore is rarely used.

'Tare Weight' is the weight of the vehicle in a condition where it’s ready to drive, but without a driver or passengers. The measurement is made without any luggage or cargo, with just 10 litres of fuel in the tank and all other fluids at their maximum level.

'Kerb Weight' is the value most often found in brochures and on manufacturers' websites. It’s also the value which causes the most confusion, and consequently errors, when trying to compare vehicle models.

In Australia and North America, kerb weight is officially defined as the vehicle in running order, unoccupied and unladen, with all fluid reservoirs filled to nominal capacity (full) including fuel, and with all standard equipment fitted (options and accessories are not included).

DIN kerb weight is measured in a similar way to the Australian definition, although the fuel level is required to be 90 per cent of the tank's capacity. DIN is a German organisation (Deutsches Institut für Normung) which defines standards for measurement.

EU kerb weight is easily calculated from the DIN weight. Quite simply, EU kerb weight is always 75kg more than DIN. The European Union adds this 75kg ballast to account for a driver and a small amount of luggage.

The heaviest that a vehicle can be is defined by the term GVW ('Gross Vehicle Weight'). Simply, the GVW is made up from the kerb weight of the vehicle plus all other loads in the car whether people, luggage, cargo, whatever. Importantly, the GVW should never be exceeded. It’s specified by the manufacturer and can be found in the owner’s handbook or on the vehicles weights label.