Why is my Subaru XT fuel-thirsty?
Subaru Forester XT. Photo/Courtesy
What you need to know:
- Hello Paul, my Subaru Forester XT is consuming a lot of fuel. I service it regularly, and I do not drive aggressively. I suspect the turbo might be the issue, but I am not sure. Could bad roads or traffic jam also be a factor? Anita
Hello Anita, it must be quite unsettling to realise that your Subaru Forester has become a fuel guzzler, especially after making what you believed were the right efforts, such as regular servicing and driving more gently.
These practices are, without a doubt, important for maintaining fuel efficiency. However, there may be other underlying issues contributing to the high fuel consumption you are experiencing.
Regular engine servicing is essential because a neglected engine often has to work harder, burning more fuel.
During service, components such as spark plugs, filters (air and fuel), and engine oil are replaced or cleaned. When these are clogged or degraded, the engine struggles to breathe and operate efficiently, resulting in higher fuel usage.
Driving habits also play a key role. Aggressive driving, characterised by rapid acceleration, harsh braking, and speeding, causes the engine to operate at high revolutions per minute (RPMs) and in lower gear ranges.
This dramatically increases fuel consumption, especially in stop-and-go traffic. That brings us to another major contributor: road and traffic conditions. Navigating through heavy traffic or on poorly maintained roads can significantly reduce your vehicle's fuel efficiency.
Crawling along in low gears or idling while stuck in a jam leads to the engine burning fuel inefficiently.
Similarly, keeping the air conditioning on while idling adds further load to the engine, translating to more fuel being burned for little or no movement Beyond driving style and road conditions, several mechanical factors might be at play. These include ageing or failing components of your engine's management system, particularly those that are not typically replaced during routine service. The oxygen sensors and air intake throttle unit, for example, are crucial in regulating how much fuel your engine uses.
Oxygen sensors monitor the amount of oxygen in the exhaust gases and help the engine control unit adjust the fuel-air mixture for optimal combustion. If these sensors are faulty due to age, carbon buildup, or electrical faults, your engine could run too rich (too much fuel), resulting in poor fuel economy.
Similarly, a dirty or malfunctioning throttle body can disrupt airflow into the engine, negatively impacting the fuel-air mixture and efficiency. To accurately pinpoint whether such components are contributing to your fuel issues, it is advisable to have a diagnosis carried out by a knowledgeable and well-equipped mechanic.
Modern diagnostic tools can quickly identify failing sensors or electronic faults that might be invisible to the naked eye. Tyre condition and pressure also have a big impact on fuel consumption.
Worn-out tyres with shallow tread depth struggle to grip the road effectively, increasing rolling resistance. This means your engine has to work harder and run at higher RPMs to maintain speed. Likewise, under-inflated tyres increase the surface area in contact with the road, creating drag and demanding more effort and fuel from the engine. Make it a habit to check your tyre pressure at least once a month or before embarking on a long journey.
The correct tyre pressure is usually displayed on a sticker on the driver’s door pillar or door jamb. Also, check the tyre tread depth.
A reliable tyre clinic or garage should have a tread depth gauge, and many tyres come with built-in tread wear indicators, which are small bars across the grooves of the tyre that show when the tyre has worn to its legal limit.
