Fuel Efficiency Myths vs Reality: Getting the Most from Your Truck

April 28, 2026

• Does being stationary use less fuel?: Turning on your car does not really use that much fuel, so avoid idling.
• Does premium diesel improve efficiency?: Premium diesel doesn’t improve efficiency for vehicles that don’t need it.
• Air conditioning uses up fuel: Air conditioning is efficient enough on motorways.
• Manual is more efficient than automatic: Modern cars are all fairly similar in terms of efficiency.
• Is a bigger vehicle better?: Most typical vehicles are efficient enough in the course of normal driving.
• Do fuel saver devices work?: No. These devices have no scientific basis
• How can I get the most from my truck?: Manage your speed with the 50-80 km/h rule, maintain proper tyre inflation, and keep your vehicle well-maintained and in good nick.

We’ve all heard those myths and roadside folklore about little driving habits and other ways we can make our trucks more efficient on the road. But some of these facts are outdated, while others have no scientific grounding. So, which of these sagas should you listen to, and which beliefs are just myths? Let’s find out more about how to get the most from your truck.

Does being stationary use less fuel?

We all know that a vehicle’s engine needs a little time to warm up before you use it. And the act of turning on the engine uses a greater spike of fuel than you’d use under normal driving or stationary running. But this leads some people to conclude that it’s more efficient to keep their rig running and idling rather than going to the trouble of stopping the engine and starting it again. However, if you have a reasonably modern vehicle, such as an Isuzu truck, the engine is designed to use minimal fuel when restarting. So, it’s best for you to turn your engine off when you’re stopping for more than a minute or two. And, never have your engine on while refuelling.

Does premium diesel improve efficiency?

Many people think that the unique makeup of high-RON diesel contains ingredients that make their truck more efficient. But this isn’t necessarily true. Unless you have a truck or other large vehicle that specifically needs high-octane rated diesel, choosing to use premium fuel in your Mack trucks isn’t efficient. With today’s fuel filters, it’s just an unnecessary expense. The most efficient thing to do is research your vehicle and stick to the recommended fuel to get the best performance without wasting money.

Air conditioning uses up fuel

It’s true that air conditioning ultimately does use some of your fuel to function. However, the amount of resources it really takes depends on where and how you’re driving. When you’re driving at lower speeds, using air conditioning definitely makes your vehicle work harder. But when you’re trucking on a motorway, using air conditioning has a less noticeable effect on your fuel. So, use that air conditioning. After all, driver comfort is vital for safety.

Manual is more efficient than automatic

In the past, automatic vehicles were thought to be less efficient than manual ones. But nowadays, advances in automatic transmission technology have brought automatic vehicles right up to speed with manual options. If you’re torn between choosing a manual vehicle and an automatic one in your search for new or used trucks, all you need to think about is your own driving style or personal preference – not fuel savings.

Is a bigger vehicle better?

Another common assumption surrounding vehicles is that bigger will always have worse fuel mileage. But under regular use, this isn’t true. These days, the majority of vehicles, regardless of spec, are designed to be most efficient at speeds between 45 and 65 km/h.

Do fuel saver devices work?

The short answer is no. Despite the claims made by some repair shops or questionable online retailers, products such as “magnetic fuel line devices” or “air bleeders” are apparently designed to make your truck more efficient in some way. However, these devices lack scientific evidence to support them. If they actually worked, truck manufacturers like Volvo or UD would already incorporate these devices into their vehicles’ design.

How can I get the most from my truck?

Now that you know the truth behind these fuel efficiency myths, how can you actually be efficient with your vehicle and get the most out of your drives?

Manage your speed – the 50-80 km/h rule

We mentioned earlier that vehicles have their best fuel efficiency between 45 and 65km/h. Above 80 km/h, fuel efficiency drops rapidly, by roughly 10% for every 5 km/h over 80. This means a truck speeding along at 85 km/h uses 27% more unnecessary fuel than a truck that’s just chugging along at 65 km/h. So, not only is speed dangerous, putting more wear on your brakes, but it’s also just not worth it for your engine.

Maintain proper tyre inflation

Tyre inflation is so important in large vehicles such as trucks, which is why we’re all encouraged to check on them as part of pre-trip inspections. Tyres underinflated by just 10 psi can increase your fuel use by 0.5-1.0%, which can add up on long journeys. For even more efficiency, try using low rolling resistance tyres, which require less energy to keep moving.

These are just a few of the ways simply keeping up with proper maintenance can help you get the most out of your vehicle.