Car Features

Did fuel consumption improving gadgets ever work


To the old maxim that there are only two certainties in life: death and taxes, there’s a third element: fuel prices continue to rise. Right from the early days of the motor vehicle came inventions that claimed to reduce the size of the hole in motorists’ pockets.


Annual Bay to Birdwood event


Despite a long list of claims made over the intervening years, it’s important to accept the fact that there are no magic potions or gadgets that have been scientifically proved to reduce fuel consumption.

Years ago and wearing different editorial hats, Gibbo and Big Al invited producers of add-ons and fuel additives to provide us with scientific test results that show a consumption improvement, but none was forthcoming. There were plenty of anecdotal reports, but no hard facts.

Testing a product to determine if it has increased fuel economy requires an automotive laboratory with sophisticated equipment. The equipment is necessary to rule out the effects of fuel potency variations, different air temperatures, humidity, driving behaviour and road conditions that can cause fuel consumption to vary 10 or 20 percent.

Many of the gadgets that were supposed to improve fuel consumption by up to 20 percent weren’t very expensive, so if they worked as claimed wouldn’t vehicle makers have fitted them as standard equipment?

Throughout the post-World War II years, the USA’s Environment Protection Agency evaluated hundreds of different ‘consumption improvers’ and found that only six had a positive effect: one was a spoiler system that made a vehicle more aerodynamic, three shut off power to accessories such as the air conditioner and the other two provided ways to decrease idling time.

You could be forgiven for thinking that gadgets to improve fuel consumption are relatively recent additions to the ‘scam catalogue’, but you’d be wrong: back in the 1920s, such devices were being heavily promoted.

HV came across an advertisement for one such device, being marketed by then-prominent department store, Anthony Horderns. 

(Anthony Horderns was known for its beautiful signposted tree on the famous Razorback Hill on the Old Hume Highway, south-west of Sydney. The signpost read: ‘While I live, I’ll grow’. Sadly, Anthony Horderns is no more and neither is the tree. The magnificent Anthony Horderns building in Sydney’s CBD is now a law court.)



In Horderns’ Mail Order catalogue, 1923, on page 924, was the following advertisement:

‘The AAA Automatic Petrol Saver Air Brake, Fits all Cars and Lorries… Simply and Cheaply Fitted. Cost 69/6’. (Incidentally, that’s $6.48, which was quite a bit of money in those days.)

The perceived need for this device was the fact that petrol had increased in price to nearly a shilling (10 cents) per gallon (a little over two cents per litre).

The AAA Automatic Petrol Saver Air Brake functioned much like a truck’s exhaust brake, increasing compression braking. The control unit fitted into a hole cut in the dashboard.



The instructions were:

‘To start engine, turn control handle to OFF. After engine is started, turn handle to ON. Keep at ON for all driving, including hill climbing. 

When going downhill keep car in gear and turn control handle to BRAKE – do not de-clutch or turn off the ignition-effective (and the) air brake will then operate. 

If brake does not act well, it is due to the throttle not closing the butterfly sufficiently, thus allowing gas (petrol) to enter cylinders, which is waste.’

To Test the mixture: 

‘When throttle is set to run the car at, say 10 to 12 miles an hour, turn control to BRAKE, and if car speed is increased, cut down benzine (petrol) immediately, as the mixture is too rich. 

When turning control handle it will be found easier to pull a little towards driver, which slightly withdraws the cone-shaped plug.’



Current fuel saving devices



Most of the products marketed since World War II fall into five basic categories: vortex generators that create swirling air flow in the air intake, magnets that strap around or connect into the fuel lines, air-bleed devices, fuel additives and oil additives.

None of the magic pills and potions, fuel line magnets or vortex generators works, according to test results from the EPA.

Magnets make your speakers function and provide detailed images of the human body, but they aren’t likely to save a cost conscious motorist any money at the gas pump, said EPA spokesman John Millett.

Vehicle owners would be better to change a few of their driving habits and make sure their vehicles are properly tuned and maintained, he said.

Claudia Bourne Farrell, a spokeswoman for the US Federal Trade Commission, said that the Commission has evaluated many products that claim to enhance performance and has not seen any that lived up to their claims.

So why do these products keep selling? Why do so many people swear by them while others are completely convinced they are scams?

All fuel economy ‘improver’ packages and labels have disclaimers that say results may vary, because of driving habits, vehicle type, vehicle condition and road conditions.

In that simple caveat lie the reasons why people can install a device or use an additive that does nothing to change fuel economy but can see an improvement in fuel economy after adding it.

Many people install vortex generators or magnets at the same time as they give their vehicles a tune-up, so the devices get the credit for the improvement in fuel economy that really resulted from the tune-up.

Many fuel consumption ‘improvement’ device makers claim that their fuel-saving function is due to improved combustion quality, but in an engine that’s correctly tuned, less than one percent of the fuel that enters the combustion chamber isn’t burned.


Real Fuel Savings


Rolling resistance and wind-resistance power demands over the years


Engine horsepower needs to supply three demands: rolling resistance power; hill climbing power and wind-resistance power. Rolling resistance power overcomes mechanical and tyre friction; hill climbing demand is the power needed to lift the vehicle up a gradient and wind-resistance demand is the power needed to overcome the friction of the atmosphere on the front, underbody and bodywork of the vehicle.

Those of us who love driving old vehicles know that they’re often heavier and less streamlined than modern vehicles and often have higher fuel consumption. Most of us keep our pride-and-joy machines for short forays and simply accept the increasing cost of fuel.

Regular servicing and maintaining correct tyre pressures are the starting points for maximum fuel economy. A well-serviced vehicle rolls freely on lubricated and adjusted wheel bearings, doesn’t have dragging brakes and its engine is operating at its optimum, with clean oil, fresh plugs and a tuned carby or clean injectors.

Tyres inflated to the maker’s recommendation roll with less resistance than under-inflated ones. 

Once you’ve taken these fuel economy steps, have a critical look at your driving style. If you don’t get high kilometres out of your tyres and brake linings you’re wasting fuel. Driving for economy means no speeding, hard braking or hard cornering.

Use anticipation when you’re driving, so you don’t have to brake to wash off speed and then have to build it up again – particularly when in traffic or towing.

Older vehicles are usually driven at lower speeds than daily drives are and that reduced speed maximises fuel economy, by reducing the amount of wind-resistance horsepower the engine needs to produce.


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