Traveling one-up in a semi-static sea of cars all headed to or from work in peak-hour traffic is practically a metaphor for envirogeddon. Not only is it the antithesis of enjoyable driving, it's a profligate waste of energy. Some in the community are quick to point an accusatory finger at motorists, but the real blame in Australia rests with state governments, which have steadfastly, over decades, allowed public-transit infrastructure to grind practically to a halt. In the absence of a viable mass-transit system, there's ... driving. And everyone does it. With the end of oil at least foreseeable, and in the face of rampant global demand, something really should be done.

Odds-on (unless you endured more than the odd propeller-headed university physics course) you've never looked at fuel consumption quite like we're about to this month.

The great truth about fuel efficiency and consumption is frequently swept under the rug, conveniently, because you probably don't think of yourself as ‘payload'. Statistically, nobody calculates their car's payload-specific fuel efficiency. Doing so gets depressing in a big hurry anyway. People consider absolutes instead - like this: Cars drink about 11 litres per 100km whereas articulated trucks gulp about 55 litres per 100km. Therefore cars are five times more fuel efficient than trucks, right?

Wrong.

Let's say you and your briefcase trot off to work; total mass 100kg. You get into the average Australian passenger car, which according to the Australian Bureau of Statistics (Survey of Motor Vehicle Use 2006) consumes 11.3 litres per 100km.

It seems pretty low - unremarkable, even - until you look at it like this: You're the payload. And you're a very small proportion of the all-up mass (probably about one-fifteenth). That means fourteen-fifteenths of the fuel you tip down the filler neck moves the metal - only one-fifteenth moves you.

If it takes 11.3 litres to move 100kg of you a distance of 100km, the ‘cost' in fuel to move one tonne of people just like you is 113 litres per 100km. This is very inefficient.

If you think of 11.3 litres per 100km as the car's absolute fuel consumption, calculating the payload-specific figure (113 litres per 100km per tonne) allows you to compare the relative efficiencies of all different kinds of transport. It normalizes all the results for payload carried - allowing apples-for-apples analyses. And the result is enough to make your head spin.

Here's how the heavyweights really stack up: