Does the Fuel Economy in a Petrol Car Decrease with Age?

Maintaining a car[1] in good condition can significantly impact its fuel economy, even as the vehicle ages. Proper maintenance practices and timely repairs can help keep a car's fuel efficiency consistent throughout its lifespan. This article explores the factors that influence fuel economy in petrol cars over time and practical ways to maintain optimal performance.

Factors Influencing Fuel Economy Over Time

There are several factors that can contribute to a decrease in fuel economy in petrol cars as they age:

Engine Wear and Tear

Over time, components such as pistons and cylinders can wear out, leading to increased clearance and reduced combustion efficiency. This can result in a loss of power and a subsequent decrease in fuel economy (My 2007 Trailblazer and 2002 Toyota Hilux examples).

Increased Friction

As all rotating parts and components wear, the friction between them increases. This additional friction can consume more energy, contributing to lower fuel efficiency. Adequate lubrication is essential to minimizing this effect.

Reduced Lubrication Pressure

Wear also leads to increased clearance, which can reduce the lubricating oil pressure, leading to increased friction further (My 2007 Trailblazer case).

Valve Leaks

Leaky intake and exhaust valves can reduce the efficiency of the engine, leading to wasted fuel (My 2007 Trailblazer case).

Proper Maintenance and Maintenance Practices

Regular maintenance and timely repairs are crucial to maintaining a car's fuel economy. Key components to focus on include:

Timely Service and Repairs

Changing the oil and oil filter at recommended intervals: This helps in maintaining lubrication and reduces friction. Replacing worn-out parts: Components like clutch, brake pads, and spark plugs can significantly affect fuel economy. Checking and maintaining the air filter: A clean air filter allows for better air intake, leading to efficient combustion.

Real-world Examples of Fuel Economy Over Time

A concrete example is my 2002 Toyota Hilux pickup. With over 627,359 kilometers on it, it has retained excellent fuel efficiency thanks to regular maintenance and care:

My 2002 Toyota Hilux

Over the 18 years of ownership:

In the first 76,308 liters of gasoline used, it achieved an average of 8.82 km/l in mixed driving conditions. Currently, after transitioning to more city driving, the average fuel consumption is 8.16 km/l. The initial two years showed an average of 8.24 km/l, followed by a steady 8.23 km/l for the first six years. From 2014 to 2016, the car saw improved mileage due to reduced trips.

Regularly adding a bottle of Techron every 5,000 kilometers has also contributed to its fuel efficiency (example).

Conclusion

Proper maintenance and timely repairs can help keep a petrol car's fuel economy consistent over its lifespan. By focusing on key components and following recommended service intervals, car owners can maximize their vehicle's efficiency, leading to lower operational costs and reduced environmental impact.

References

[1] Car Driver magazine; Various tests on fuel efficiency over time.