MOTORING NEWS - Les Mc Master, chairman of the Motor Industry Workshop Association (MIWA), says while fuel efficiency tips may have worked in the past where vehicles had less sophisticated components, most don't apply anymore since vehicles manufactured today have computer-controlled automotive systems.
"Fuel efficiency is still a consideration especially with the imminent fuel price increase expected at the end of the month. The fuel price relief we have experienced recently seems about to turn with an approximate R2 per litre increase expected."
It's probably a good idea to know the truth about many fuel efficiency tales he commented on below.
This idea may have been relevant when engines used carburettors, but today's cars have computerised fuel-injection systems. These systems sense if an engine is revving above idle when you ease off the accelerator. If that happens, the fuel injectors shut off, so fuel is no longer injected into the engine, even if the car is still in gear. By constantly shifting in and out of neutral the only thing you may accomplish is premature wear on your gear box.
The idea that a tank more full than empty will prevent fuel evaporation inside the tank is incorrect. Fuel systems in modern cars are designed with vapour recovery systems so no evaporation is possible. Some vehicles with pressurised fuel systems even display a 'check engine' light if the petrol cap is loose, missing or not properly sealed.
The engines in older vehicles pulled air straight through the air filter into the carburettor, so a clogged filter could affect fuel efficiency to some degree. However today's advanced engines have a computerised engine control module (ECM) to regulate the air-to-fuel ratio.
Air goes through the filter and then through a mass airflow sensor that lets the ECM gauge the airflow and adjust the fuel accordingly; less airflow means less fuel is sent to the engine. While fuel efficiency may not be affected, dirty air filters can lead to sluggish acceleration.
For years, a myth has been circulating that if you buy petrol during the cooler part of the day you get more for your money, since a cooler liquid is denser. This theory may sound believable but at filling stations petrol is almost always pumped from storage tanks underground that are naturally insulated from large temperature swings.
Because of this, any slight change in the temperature of the petrol is so small you wouldn't notice any real savings.
Cruising downhill in neutral saves petrol
This is one of the biggest myths around. The truth is that when coasting in neutral, the engine is idling, consuming just as much petrol as when it's idling at a traffic light or warming up in your driveway. The reality is that it's a bad idea to roll downhill or up to a stop sign in neutral. One might need to be able to use the accelerator to avoid any unexpected road hazard.
Cars don't handle well in neutral during sharp cornering manoeuvres when the engine isn't connected to the drivetrain - the components in the vehicle that generate power.
Be aware of claims made by manufacturers regarding fuel saving devices. There are a number of different devices doing the rounds and each one is purported to have magical fuel saving powers, be it a magnet device connected to the fuel supply line that 'aligns' the atoms in the fuel by electromagnetic field, to the swirl or vortex device that is fitted to the intake manifold.
vehicle. Be cautious of marketing ploys and before you consider purchasing such a device, seek the expertise of your nearest MIWA dealer to guide your decision making.
Many gullible consumers have been duped into doing costly damage to their vehicle by the unscrupulous marketers of these devices. "If in doubt, rather ask an expert," says Mc Master.
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