![\"fuel-consumption\"](\"http:\/\/blog.privatefleet.com.au\/wp-content\/uploads\/2013\/02\/fuel-consumption.png\" "\\"fuel-consumption\\"")
<\/a><\/p>\nIt was perhaps the energy crisis of the early 1970s which first gave pause for them to consider just how much fossil fuel their products were burning as they supplied mass transportation to the world. Since that time, mechanical carburettors have been surpassed by electronically-controlled fuel injection, a far more efficient and accurate method of supplying fuel to the engine. This process has been refined further, with today\u2019s \u2018direct injection\u2019 petrol motors providing excellent engine response and power while also being frugal with fuel. Additionally, diesel engines have found wide-spread acceptance across the globe thanks to their headline fuel consumption figures (though their pollutant levels are another matter).<\/p>\n
When shopping for a new vehicle today, the government has ensured that Australians have a set of combined fuel consumption figures which allow us to directly compare rival models. Set under Australian Design Rule 81\/02, manufacturers have to provide a windscreen sticker on all new cars which shows \u2018urban\u2019, \u2018extra-urban\u2019 and \u2018combined\u2019 fuel consumption in litres per 100 kilometres.<\/p>\n
How are these figures arrived at?<\/p>\n
Using a chassis dynamometer in a workshop, a sample vehicle is strapped on to the machine\u2019s rollers and taken for a stationery spin. Each car uses either pump-grade diesel fuel or 95-octane unleaded fuel to ensure there is no fuel advantage. It is then run over 20 minutes, simulating the stop-start conditions of an urban drive, followed with a sustained run up to freeway speeds. The figures garnered are then merged to provide the headline \u2018combined fuel use\u2019 figure.<\/p>\n
Although these tests are thorough- they use fans to simulate air-flow and the rollers to generate inertia- it is nevertheless very difficult to paint a truly accurate picture of that vehicle\u2019s performance on the road; the external variables are too great.
\nThink of everyone you\u2019ve ever sat next to as they drove. They all have their own driving habits, and that affects fuel use. Other variables, such as the road surface, gradients, altitude, temperature, fuel quality\u2026the list goes on.<\/p>\n
In practice it is our experience that the simulated figures are very difficult to emulate in real-world conditions, particularly with modern smaller-capacity turbocharged cars (not to mention the traditional large-capacity V8s) when you want to use the available performance- which is the point of buying such a car in the first place.<\/p>\n