Missing Gear Changes: Saving Fuel, Improving Efficiency

Missing out on some gear changes can help save fuel by reducing the amount of time spent accelerating. Fuel consumption is at its highest when accelerating, so skipping gears can lead to fuel savings. For example, driving at 60 mph in third gear will use up to 25% more fuel than in fifth gear. Additionally, modern cars have advanced fuel injection systems that cut the fuel supply when the driver lifts their foot off the accelerator while the car is in gear. Therefore, it is more fuel-efficient to shift to a higher gear when it is safe and practical to do so, rather than coasting in neutral.

Higher gears = lower engine speed

Driving in higher gears at lower engine speeds can help you save fuel. This is because fuel consumption is directly related to the load on the engine, which is determined by the amount of work the engine has to do. When you drive at a higher gear, you increase fuel economy and reduce fuel consumption.

Fuel consumption is determined by the engine's RPM (rotations per minute) and the throttle setting. The RPM determines how often a single charge of fuel/air mixture is burned in a cylinder, while the throttle setting controls how much fuel is in that charge. By choosing the right combination of RPM and throttle setting, you can get the same amount of work from the engine, regardless of the RPM.

At lower RPMs, you need to open the throttle more to burn more fuel per cycle. Conversely, at higher RPMs, you need to open the throttle less, burning less fuel per cycle because the cycles come more frequently. Therefore, you can reduce fuel consumption slightly by using a higher gear and lower RPM for a given load condition.

Additionally, when accelerating, you can save fuel by changing gears smoothly and gradually. This is because fuel consumption is at its highest when accelerating. By missing out on some intermediate gears, you can reduce the amount of time spent accelerating and, consequently, the amount of fuel used.

Less time spent accelerating

Fuel consumption is at its highest when accelerating. By reducing the amount of time spent accelerating, you can save fuel. This can be achieved by missing out some gear changes.

When accelerating between each gear, more fuel is injected into the engine than if you had maintained constant acceleration. Therefore, fewer gear changes mean less fuel is used. It is not always necessary to change up or down through each gear.

Analysis by the Massachusetts Institute of Technology shows that aggressive driving behaviour, characterised by speeding and rapid acceleration and braking, can lower fuel economy by 15–30% at highway speeds and 10–40% in stop-and-go traffic.

It is worth noting that there are other factors at play when it comes to fuel efficiency. For example, the type of vehicle, driving conditions, and driving behaviour all impact fuel consumption. Additionally, the relationship between acceleration and fuel economy is complex and can vary depending on the specific vehicle and driving conditions.

Less fuel injected into the engine

Missing gear changes can help save fuel by reducing the amount of time spent accelerating. Fuel consumption is at its highest when accelerating, so by skipping certain gears, you can maintain more constant acceleration and use less fuel.

When you accelerate between each gear, more fuel is injected into the engine than if you were to maintain a more constant acceleration. Therefore, fewer gear changes mean less fuel is injected into the engine and used overall.

Modern cars are equipped with a Deceleration Fuel Cut-Off (DFCO) system, which cuts the fuel flow to the engine when the gas pedal is not depressed and the car is in gear. In this case, staying in gear is more fuel-efficient than being in neutral because you are letting gravity run the engine instead of fuel.

Additionally, staying in gear while going downhill saves wear on your brakes. The partial vacuum created in the engine leads to engine braking, which provides better control over the vehicle.

Less need to use the footbrake

Skipping gears while driving can help you save fuel by reducing the amount of time spent accelerating. This, in turn, leads to less frequent use of the footbrake.

When you accelerate, more fuel is injected into the engine compared to when you maintain a constant speed. Therefore, by skipping intermediate gears, you can maintain constant acceleration and avoid the increased fuel consumption associated with accelerating from lower gears.

For example, when driving a manual car, you can shift directly from second to fourth gear when accelerating, rather than going through each gear sequentially. This approach reduces the time spent accelerating and lowers fuel consumption.

Additionally, by skipping gears and maintaining a more constant speed, you can minimise the need to use your footbrake. This is because you are already travelling at a slower speed, closer to the desired speed you want to achieve after braking. As a result, you avoid the fuel-intensive process of accelerating from a complete stop, which requires a significant amount of fuel to get the car moving again.

Overall, by skipping gears and reducing acceleration, you not only save fuel but also decrease the wear and tear on your brakes, as they are used less frequently and with less force. This dual benefit of fuel savings and reduced brake maintenance makes skipping gears an attractive option for those looking to optimise their vehicle's performance and reduce operating costs.

Control the amount of steering

The steering system in your vehicle is designed to guide your car, but it can also impact how much fuel your car uses. By controlling the amount of steering, you can help to save fuel. Here's how:

• Maintain proper wheel alignment: If your wheels are not aligned properly, they will not roll freely, forcing the engine to work harder to keep the vehicle moving, which increases fuel consumption. Regular wheel alignment checks, at least once a year or whenever you notice any pulling or steering issues, can help ensure your tires roll straight and evenly, reducing resistance and improving fuel efficiency.
• Keep power steering fluid in good condition: In hydraulic power steering systems, low or contaminated power steering fluid makes it harder for the steering pump to function, causing added strain on the system and making the engine work harder, which consumes more fuel. Regularly flushing and replacing your power steering fluid can keep the system lubricated and functioning efficiently, reducing engine strain.
• Choose electric power steering: Electric power steering systems can increase fuel efficiency by removing the hydraulic pump and steering box, which cause parasitic drag on the engine. Electric power steering only consumes voltage when active, saving fuel.
• Minimize sharp turns and excessive steering: Sharp turns and excessive steering can increase fuel consumption. Drive smoothly and avoid abrupt turns or rapid changes in direction to optimize fuel efficiency.
• Maintain proper tire pressure: Keeping your tires properly inflated can reduce rolling resistance, making it easier for the steering system to control the vehicle and improving fuel efficiency.

By understanding the connection between your steering system and fuel efficiency, you can make small adjustments to your driving habits and vehicle maintenance routines to optimize fuel economy and save money.

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