Fuel Consumption Comparison: What You Need To Know

Although we hate having to fork out for it, petrol is a necessary expense. On average, Australians pay $79.45 per week on fuel, and according to the Australian Automobile Association’s (AAA) Transport Affordability Index Reports, the trend is continuing to rise each quarter.


But fuel consumption comparison isn’t as straightforward as it seems. In this article we get to the bottom of the efficiency and environmental impacts of the different types of fuel, so you can choose a car that’s right for you and stretch your money further.


How to read Fuel Consumption Labels


The figures on the Fuel Consumption Labels provide the number of litres a particular model of car consumes for every 100 kilometres it travels. The testing is done in a laboratory to simulate different driving conditions.


  1. Combined average L/100km
  2. Urban average L/100km
  3. Extra Urban L/100km


The Urban figure is designed to represent fuel consumption while driving in inner-city conditions with heavy, stop-start, local traffic.


The Extra Urban figure represents fuel consumption at slightly higher average speeds, slightly longer distances and includes trips with acceleration to reach highway speeds.


The Combined average is exactly as it says – a figure that includes a combination of both these types of driving conditions.


But these figures are just a guide.


Even the research recognises there are big discrepancies between official test results and real-world fuel consumption. This is because they can’t possibly take into account all the different variants that affect consumption in real-world conditions.


In everyday life, things like traffic conditions, vehicle condition, load, engine size and even how you drive your car, will affect how much fuel your car consumes. And while 6L/100kms on the label is considered pretty good, it’s probably realistic to expect your real-life consumption will be a bit higher.


The low down on diesel fuel comparison


Have you ever considered buying a diesel? No? Then you might want to reconsider because diesel engines are more efficient than petrol by a whopping 30-40%. So, what’s the catch?


Yep, you guessed it. Diesel fuel costs more than petrol. And you can also expect to pay a few thousand more for the privilege of owning one, but they also retain their value at time of sale.


Diesel engines are also more complex, meaning they have slightly higher servicing costs. And if you’re buying a second hand diesel car or SUV, it’s probably worth getting it checked by a specialist diesel mechanic before you drive away.


While diesel cars emit similar C02 as petrol engines, they produce more toxic hydrocarbons, oxides of nitrogen and particulate matter which is a bigger problem in areas with higher population density, and why parts of Europe have begun banning diesel engines.


In Australia however, the sale of diesels  and engine technology now includes particulate filters to reduce the unavoidable toxic emissions. With the sale of diesel powered cars still strong in Australia, improved engine technology now includes particulate filters to reduce the unavoidable toxic emissions. There is one caveat though.


Inner city driving isn’t going to give you the cost benefits you’re looking for in a diesel engine. They reach peak efficiency while cruising at constant speeds, and suit drivers who regularly use the highway. So, they might be better for drivers who regularly do longer trips, or who need the power to tow heavier loads for longer distances.


Petrol fuel comparison


Petrol cars are just plain thirsty. They use more fuel than diesel engines but it’s (only slightly) cheaper at the bowser. They’re quick off the mark, making them better for stop-start, inner city and suburban driving. But their consumption comes from acceleration.


Petrol engines get their power at higher REVS, meaning you use the most fuel when you need to plant your foot to reach and maintain higher speeds, overtake or climb hills. This makes them ideal for urban driving conditions where acceleration can be managed. The easiest way to save money on fuel in a petrol car is to take notice of how you drive. Accelerating smoothly will help you reach speed while minimising the fuel your engine guzzles.


Petrol cars remain the most popular choice of car in Australia, perhaps because they cost less to purchase, and maintenance and servicing costs are slightly less. Petrol has comparative C02 emissions to diesel, but don’t have the same issues with other toxic emissions due to self-regulating catalytic converters inside the cars.


LPG fuel consumption comparison


While it’s on the decline, LPG is the kindest on emissions and on engines. The price for LPG is also around 50-60% cheaper at the pump. The catch? Cars using LPG (propane/butane or mix) consume way more fuel than any other type of car (about 20% more than petrol). So, you’re going to be intimately acquainted with your local servo – if you can find one that still has LPG.


Yep. The sale of LPG is on the decline. Before their closure in Australia, big manufacturers like Ford and Holden used to fit their 6 cylinder Falcons and Commodores with LPG to offset the cost of petrol in a larger 6 cylinder engine. Now there’s no new cars manufactured with LPG, and while you can still convert an existing petrol engine, you’re looking at a cost of $3000 – $5000 to do so.


What are the other benefits? LPG can potentially prolong engine life because engine oil and spark plugs need changing less often. But it’s been speculated that cheaper servicing costs might climb as the cars get rarer.


And if you’re planning a road-trip in the near future, they’re probably not the car for you. A combination of their fuel-guzzling nature, and the increasing rarity of LPG will mean you need to plan your trip well, to ensure you don’t run dry. We’re guessing this might turn most people off.


So, whats the most economic choice for you?


To make the best choice about fuel consumption use the label as a guide, but consider your budget, your circumstances and driving style. In combination with the info above, these questions might help you decide.


What kind of driver are you?


  1. A take-your-time-but-leave-early-driver, who is chill behind the wheel
  2. A competitive and impatient lead-foot (with a bad tailgating habit)
  3. Relaxed, but likes to get to speed quickly so I don’t hold people up


What type of driving do you do most?


  1. Short trips that are mostly local, inner city and suburban driving
  2. Suburban driving, with an average of 15 – 30 mins in a car
  3. Regular highway driving (about an hour each week) but usually not far
  4. Lots of interstate travelling, on highways and some local


What size car do I need?


  1. A medium passenger car that has room for a few passengers
  2. A small car I can zip around town in on my own or with one friend or two
  3. A small SUV/large passenger car with room for extra gear/surf board/camping/kids sports stuff/work merch
  4. A medium SUV with room for passengers and tools or work gear/camping gear and luggage for road-tripping/4WDing
  5. A large SUV/People mover (or something bigger) with room to haul lots of stuff and a few extra people


Over to you


How much do you spend on petrol each week? Have you considered buying something other than a petrol car before? We’d love to know.

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