Hopefully not to the dangerous extremes taken by an 80-something-year-old woman from country Victoria.

I heard this story from a woman I know through work and she's kindly let me share. A few years ago she received a call from the police, letting her know her grandmother had been booked under the state's anti-hooning laws, her car had been impounded, and could a family member please come and pick her up.

It turned out the grandmother, driving around the hilly terrain of the Yarra Valley, so resented the cost of the petrol she burned driving up the hills, that she'd put the car in neutral and coast down the hills to try to recoup the cost. The idea was to let gravity give the car enough oomph to partially climb the next hill before she had to put the car back in gear and start burning fuel again.

Until she was caught, the grandmother was quite proud of this nifty fuel-saving technique and called her car, which at the time carried a number plate starting SFO, the “Silver Flying Object”.

To fall foul of anti-hooning laws, you had to be exceeding the speed limit by more than 30km an hour, plus a 3km buffer. The police radar said she was doing 125km in a 90km zone.

At the time the Victorian police were not meant to use radar on cars driving down hill. Evidently the police caught her going up the hill in neutral at 125km an hour, so her downhill speed must have been much faster.

The grandmother lost her licence for 30 days, was fined about $800-900 and lost a hefty number of demerit points. Family members paid the fine, worried that if she went to such lengths to save a bit of petrol, there was no telling what she might do if she felt she had to somehow recover $900.

The family then persuaded her to get rid of her car and organised a new one. “We’ve got good news and bad news,” they said. “The good news is your new car has FM radio [the previous one only had AM]. The bad news is we’ve bought you an automatic – if you try putting it in neutral, the steering wheel will lock and you’ll run into a tree.”

Thus Australia’s oldest hoon had her wings clipped for the remainder of her driving career.

Most people wouldn’t go to such lengths but I did have one Twitter contact who disclosed he once drank instant coffee rather than spend the money on petrol driving somewhere with espresso. Now that’s hardcore!

I jest, but it’s true that petrol costs loom large in the budgets of most Australian households.

I’m lucky to live close to the city so I walk most places and take public transport. While we haven’t dispensed with a car altogether like some inner-city families, we’re a one-car family and we fill up every two to three weeks.

But most Australians spend a lot more time on the road than my family, and the cost of running a vehicle is significant.

The Australian Automobile Association publishes a Transport Affordability Index that includes both public transport and vehicle running costs. The latest figures, from December 2017, suggest city households spend $17,606 annually on transport costs, accounting for 14.2 per cent of household incomes.

Sydney is the most expensive city overall, with households spending $22,292 a year, but ranks third when expressed as a share of income. Brisbane is the most expensive city for transport as a proportion of income, while Canberra is the most affordable.

Regional households are spending $14,008 annually on transport, comprising 12.3 per cent of household incomes.

Now, these figures are a little rubbery, because they include the cost of car repayments and assumes a near-new car funded by a loan. But fuel is a significant cost. The index estimates the petrol bill for the average household is $69.52 a week in the cities and that’s assuming only one partner in a couple drives to work and the other takes public transport. Regional households are paying $73.46 a week for petrol, though other costs such as tolls and public transport are lower.

Separately, figures from the 2016 Census analysed by social research company McCrindle suggest that of the nine million daily commuters in Australia, almost seven out of 10 commute by private car. Given inner-city households like mine have two workers using public transport, it’s likely a lot of suburban and regional households have two people driving to work – and higher costs as a result.

Technology is making it easier to save fuel.

An obvious place to start is to check petrol price apps such as MotorMout or the NSW government-backed Fuel Track – though remember it would be a false economy to drive miles out of your way to save a few cents on petrol.

But a recent report from the Organisation of Economic Cooperation and Development (OECD) concluded compulsory fuel price reporting laws have not provided significant consumer benefits, and are instead being used by the service stations for “tacit collusion” over prices.

There are also apps to let you lock in fuel prices - I had an Uber driver who recommends the 7-Eleven Fuel app. Fuel is generally cheaper at the start of the weeks so he locks in the price on a Monday or Tuesday, then gets the benefit of it later in the week. It's free, so if he guesses wrong,  he can just shop elsewhere.

Another option is car pooling. Look up the well-established, not-for-profit group Community Car Pooling, which has thousands of members.

Then there are telematics tools such as GOFAR – essentially a fitness tracker for your car. A donlge plugs into your diagnostic port and a device called "Ray" on your dashboard provides feedback - glowing blue when driving is efficient and pink or red when the car is being driven poorly.

The idea is to help you find the sweet spot in acceleration where you’re maximising the power from the engine for the least amount of fuel. The company claims GOFAR users enjoyed average fuel savings of 9.8 per cent in 80,000km of driving tests.

Of course, it won't work if you're coasting in neutral.

Caitlin Fitzsimmons is the Money editor. Facebook: @caitlinfitzsimmons. Twitter: @niltiac.