Fuel Economy: Myths Vs Facts


Dec 01st, 2021

Fuel Economy: Myths Vs Facts

There is nothing more welcome to a car owner or driver than finding a way to save on car fuel or improving on fuel economy. 

Finding a way to save on fuel consumption is a big win as you get more kilometres with every litre of fuel and take longer to visit the bowser.

I bet you’ve heard all those tips and tales about how to save on gas. Are they true? I’m sure half of them aren’t, but I still fall for them anyway. You know, it’s often a case of – If it won’t hurt, then I may as well give it try.

However, not all seemingly harmless fuel-saving hacks are entirely harmless. And if they are, they almost always entail buying something, which adds up to the cost and results in you spending more instead of saving a few platypuses.

So which fuel economy hacks are for real, and which are just myths? Let’s hear them all for the one last time.

20 Fuel Economy Hacks: Myth vs Fact

1. Using fuel additives increases fuel efficiency – Myth

Fact: There is no magic fix in those fuel additive bottles, and this has even led some countries to regulate the sale of these products to protect consumers. 

The only fuel additive that works is the fuel injector cleaner, and it only works on dirty and clogged fuel injectors. Yes, when your injectors are clean, they work more efficiently, bringing back your vehicle to the original fuel economy before it went dirty. 

Even with fuel injector cleaners, you cannot say that they increase in fuel economy. What they do instead is restore fuel efficiency. 

2. Using aftermarket electronic fuel-saving devices increases fuel economy – Myth

Fact: This myth is widely sold by the device manufacturers and distributors. On the contrary, many of these devices increase tailpipe emissions and are destructive to the engine.

3. You need to warm up your vehicle before driving to save on fuel – Not True to All 

Fact: Only in the older vehicle models do you need to heat the engine. The modern engines are ready to drive seconds after the engine starts. However, when carrying weighty loads, avoid driving your vehicle until it warms up.

4. Driving on high speed is more fuel-efficient – Not Always True

Fact: Under ideal conditions, yes, it’s true. However, this statement cannot be accepted as a general truth or fact. Terrain and other external conditions dictate how fast you can travel to achieve optimum fuel efficiency. 

For example, in windy conditions, driving at high speed increases the aerodynamic drag and reduces fuel economy. Also, maintaining high speeds when driving uphill requires pushing harder on the accelerator and burning excessive fuel, which no doubt lowers the fuel economy.

5. Using premium petrol improves fuel efficiency – Myth

Fact: There is a misconception that premium fuels give better fuel economy, which is false. If your vehicle is not built to use premium fuel, it will not perform better and may even perform poorly than when using the recommended fuel. 

6. Lowering the tailgate, removing it, or using an aftermarket net instead of the actual tailgate saves on fuel for pickups – Myth

Fact: On the contrary, when the tailgate is up, it is better for aerodynamics. Lowering or removing the tailgate affects the aerodynamic efficiency, and using a net is worse since it acts like a fishing boat dragging the fishing net. This results in even increasing the fuel consumption instead of lowering it.

7. Driving with closed car windows saves on fuel – Myth

Fact: You are probably aware that driving with open windows negatively affects the aerodynamics of your vehicle leading to higher consumption of fuel. Nonetheless, this does not mean that driving with your windows up will increase your fuel efficiency. 

Driving with car windows closed may force you to use the vehicle’s air conditioner, which drains power from the engine leading to decreased fuel efficiency.

Either way, you don’t ‘save’ fuel substantially, so the decision to close or open your window should not be based on this futile fuel-saving idea.

8. Cruise control improves your vehicle fuel efficiency – Not Always True

Fact: Cruise control does not always improve your fuel efficiency. It only enhances the fuel efficiency on longer drives on generally flat terrains. 

On roads with varying terrain, you may experience sudden acceleration when your vehicle is going uphill on cruise control. That rapid acceleration burns excessive fuel like when you over-push on the gas pedal and is a reduction in fuel efficiency. 

9. Your vehicle’s fuel efficiency will decrease with age – Not Necessarily True

Fact: The effect of age on fuel efficiency is negligible as long as you service the car on time as recommended.

Poor car maintenance is what causes the decline in fuel efficiency and not age per se. Studies have shown the effectiveness of engines to remain almost constant over extended usage with correct and regular car servicing, timely replacement of worn-out parts, and non-abusive use of the vehicle.

10. Shifting your vehicle to neutral when you stop saves on fuel consumption – Not True to All

Fact: This is only true in older cars with carburettors. The modern automobiles have computerised fuel injectors, and it doesn’t matter whether you are on neutral or on in gear, the system cuts off the fuel supply when you ease off the accelerator. Fuel is injected when you rev on the throttle, and constant shifting to neutral doesn't save on fuel; instead, it leads to early wear of the shifting system.

11. Maintaining your vehicle on idle mode is more fuel-efficient than starting and switching off the engine – Not True to All

Fact: Similarly, this could have been true with the older car model but not in the new fuel-injected car model. These fuel-injected modern cars start very efficiently once the engine has warmed up, and they consume less when starting. 

Switching off the car engine may be more fuel-efficient than idling, which can use up approximately 2 litres of fuel per hour (0.5 gallons/hour) in most vehicles. It is wise to turn off your car unless you’re waiting for only brief periods between drives.

12. Changing air filters will increase the fuel economy of a vehicle – Not True to All

Fact: Unfortunately, this is only true for older car models with carburettors and not the new models. The modern engines are fitted with on-board computer-PCUs and ECU and do not necessarily rely on the amount of air intake. Instead, they operate on air-fuel ratio, so while a cleaner filter improves engine efficiency, it does not affect fuel efficiency.

13. A manual gearbox always translates to better fuel economy than an automatic transmission – Not Necessarily True

Fact: In traffic jams, a manual gearbox has less fuel economy than an automatic transmission. Previously, manual transmission vehicles gave better fuel economy in highways with less traffic, but today, things have changed with the improvement in the efficiency of the automatic models. 

Currently, the modern automatic models perform the same or much better than their manual counterparts translating to better fuel economy.

14. A small engine vehicle translates to better fuel economy – Generally True but Not Always

Fact: Small engines will not always give you better fuel economy. On busy streets and with lighter loads, the small-engine vehicles may be more efficient, but on high-speed highways and heavier loads, the bigger-size engines are more fuel-efficient. 

Besides, modern inventions such as hybrids, turbocharging, advanced tyres with less rolling resistance, advanced fuel injections, and improved transmissions significantly improve the fuel efficiency of standard-sized automobiles. 

15. Refuelling when it is cooler gets you more fuel than when it is hot – Myth

I can only surmise, but I guess the assumption here is this: Fuel, like most forms of matter, expands when heated (fact), and thus you might get less for the money if you buy fuel that’s expanded from its actual volume due to the high ambient temperature (ridiculous).

Fact: Fuel is stored underground in insulated storage tanks from where it is pumped to your vehicle. The change in temperature underground is very minimal, let alone the fact that the fuel storage tanks are also insulated. 

As a result, there may be no difference in the amount of fuel pumped into your vehicle, whether it is cold or hot. The difference, if at all, may be very insignificant.

16. Maintaining the fuel tank more full than empty reduces evaporation and increases fuel economy – Not True to All

Fact: It is a fact that fuel evaporates and the bigger the surface area and evaporation space, the higher the evaporation. However, unlike the older cars that allow fuel vapour to escape, modern vehicles have a vapour recovery system, and nothing goes to waste. 

The modern automobiles have air-tight fuel tanks and even display the check engine warning when you attempt to drive the vehicle with the cap not appropriately closed.

17. Slow cruise saves on fuel – Myth

Fact: This is a myth, and slow drives do not necessarily save on fuels like driving on high speed. Most vehicles achieve their maximum full efficiency on moderate rates of 80-95 km/hr (50-60 miles per hour).

18. Close-trailing big vehicles translates to fuel economy – True, But

Fact: Following a bigger vehicle closely indeed improves fuel economy. The idea is that the bigger lead vehicle shields the trailing smaller vehicle from the oncoming wind, and the draft created by the bigger track has some pulling effect. 

However, this is only a hypothetical situation. In typical cases, trailing another vehicle dangerously close (and a big one at that) is risky and entails sudden accelerations and braking to keep up and avoid bumping into the lead vehicles.

Sudden braking and accelerations are fuel-inefficient and in fact cancel out whatever fuel efficiency achieved from the wind shielding and draft pull. Consequently, close-trailing in typical scenarios yields insignificant fuel efficiency and poses significant hazards.

19. Smaller independent refuelling stations sell spurious fuel with lower fuel efficiency – Mostly False & Malicious

Fact: Most independently-owned fuel stations acquire their fuel from prominent companies. These smaller players are in a competitive business, and they cannot risk their reputation, which can be more damaging and more costly to rebuild than those of more prominent blockchain fuel outlets. 

They must sell genuine good quality fuel to maintain their reputation, stay competitive, and thrive in their business.

20. Over-inflating the tyres improves a vehicle's fuel efficiency – Myth

Fact: Increasing the tyre pressure reduces the rolling resistance of a tyre. However, every tyre has the recommended pressure, and over-inflating it has more disadvantages than advantages. 

The amount of cash you would save from fuel efficiency is insignificant compared to the cost you would incur from over-inflating, such as premature wearing out of the tyres.

Do not be misinformed by fuel economy hacks since many of those are nothing but myths and a waste of your time and money. Get a full guide of verified ways to improve the fuel efficiency of your vehicle from Car Part Australia and avoid falling victim to con people who benefit from these myths.

Validating a Car Economy Hack

OK, so you might thing that it’s quite easy to dismiss one hack to another as a myth. Well, you really don’t have to take my word (or anybody’s) for it – you can validate what you hear for yourself.

Say, you have a hack that you feel is true and would like to try. By all means, try it, as long as you don’t endanger yourself or cause damage to your engine or car.

Then validate with numbers because numbers don’t lie. Here’s a dirty trick in calculating fuel economy.

How to Calculate Fuel Economy

It’s as simple as comparing two situations. Remember your science experiments in grade school? You better because you’ll do some experimenting for 2 weeks:

Situ A: For 1 week, drive as you usually do, make sure you have gas to last a week without refuelling. On the first day, record your initial odometer reading and initial fuel level. At the end of the week, read and record the latest odometer reading and fuel level. 

  • Step 1: Find the difference between the initial and final odometer readings – that’s your distance travelled in kilometres (km)
  • Step 2: Do the same with the two fuel readings – that’s your fuel consumption in litres (L)
  • Step 3: Calculate fuel consumption: divide the result in Step 1 by the result in Step 2 – this will tell you how many kilometres your car gets you for every litre of fuel you fill in

Situ B: Do the same for another week, making sure that your driving routes and travel times are as close as possible to Situ A. The only difference is that you incorporate the hack you want to prove/disprove. Record the same data as before.

  • Step 1: Determine the distance travelled in km
  • Step 2: Determine fuel consumption in L
  • Step 3: Calculate fuel economy: km/L

Now you have everything you need. Compare the fuel consumption in Situs A and B and see if there’s a difference.

If the fuel economy with the hack is significantly bigger, then there’s a good chance that it’s true. You’ll want to try it several times to make sure it’s not a fluke. 

If you really want to save on fuel, it’s more important to focus on keeping your fuel system clean, servicing your car regularly, and only buying cars with the best fuel economy in the first place!