Why is my real fuel consumption worse than the official rating?

Official figures come from a standardised laboratory cycle that no real journey resembles. Short trips from cold, urban stop-start traffic, highway speeds above about ninety kilometres per hour, roof racks, towing, air conditioning, under-inflated tyres and a heavy load all push consumption up. A gap of fifteen to thirty per cent between the sticker and reality is entirely normal.

How should I estimate drive time?

Take the route distance and divide by a realistic average speed rather than the speed limit. Long highway drives average well below the posted limit once towns, roadworks and traffic are included. Then add breaks: the standard advice is a rest stop roughly every two hours, plus meal stops and fuel. Those additions are usually what makes an estimate wrong, not the driving itself.

Auto & Travel calculators

Fuel cost, fuel efficiency, and trip planner calculators

4 calculators

Car and travel calculators answer the practical pre-trip questions: what the fuel will cost, what your vehicle is actually consuming rather than what the brochure claimed, and how long a drive really takes once breaks are included.

They handle both metric and imperial conventions, because the same trip is quoted as litres per hundred kilometres in Australia and miles per gallon in the United States, and the two move in opposite directions. A higher figure is better in one and worse in the other.

Start with these in Auto & Travel

Fuel Cost CalculatorWork out what a trip will cost in fuel from distance, fuel economy and price, one way or return, split between passengers, in metric, US or UK units.Auto & Travel Fuel Efficiency CalculatorMeasure your real fuel economy from distance and fuel used, convert it between L/100km, US mpg and UK mpg, and compare it with the official label figure.Auto & Travel Tyre Size Comparison CalculatorCompare two tyre sizes for overall diameter, sidewall height, revolutions per kilometre and the speedometer error a change introduces.Auto & Travel Road Trip Planner CalculatorPlan a road trip with drive time, rest breaks, days on the road, refuelling stops and fuel cost from distance, speed, economy and tank size.Auto & Travel Car Running Cost CalculatorCalculate the true yearly, monthly and per kilometre cost of owning a car in Australia, including fuel, insurance, registration, servicing, tyres, finance interest and depreciation.Australian Finance EV vs Petrol Cost CalculatorCompare the running and ownership cost of an electric car with a petrol car in Australia: energy cost per 100 km, home and public charging, servicing, the break-even point and total cost.Australian Finance

Every Auto & Travel calculator

4 calculators

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Road Trip Planner CalculatorPlan a road trip with drive time, rest breaks, days on the road, refuelling stops and fuel cost from distance, speed, economy and tank size.

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Tyre Size Comparison CalculatorCompare two tyre sizes for overall diameter, sidewall height, revolutions per kilometre and the speedometer error a change introduces.

Questions about auto & travel calculators

Why is my real fuel consumption worse than the official rating?: Official figures come from a standardised laboratory cycle that no real journey resembles. Short trips from cold, urban stop-start traffic, highway speeds above about ninety kilometres per hour, roof racks, towing, air conditioning, under-inflated tyres and a heavy load all push consumption up. A gap of fifteen to thirty per cent between the sticker and reality is entirely normal.
How should I estimate drive time?: Take the route distance and divide by a realistic average speed rather than the speed limit. Long highway drives average well below the posted limit once towns, roadworks and traffic are included. Then add breaks: the standard advice is a rest stop roughly every two hours, plus meal stops and fuel. Those additions are usually what makes an estimate wrong, not the driving itself.