2006 Infiniti G35 Gas Mileage

The 2006 Infiniti G35, a popular choice among enthusiasts for its blend of luxury and performance, has a fuel economy that often becomes a topic of interest. Understanding the factors that influence its gas mileage can help owners optimize their driving habits and maintenance routines. This article dives deep into the fuel consumption characteristics of the 2006 G35, providing insights relevant to DIY mechanics and experienced car owners.

Understanding the 2006 Infiniti G35 Engine and Drivetrain

The heart of the 2006 G35 is the VQ35DE engine, a 3.5-liter V6 renowned for its smooth power delivery and robust construction. This engine, a staple in Nissan and Infiniti vehicles for many years, employs Dual Overhead Camshafts (DOHC) and Variable Valve Timing (VVT) to optimize performance and efficiency. Understanding these key components is crucial for diagnosing and addressing fuel economy issues.

DOHC means that the engine has two camshafts per cylinder bank, one for intake valves and one for exhaust valves. This allows for more precise valve control, contributing to better engine breathing and improved combustion efficiency. VVT, specifically Nissan's Continuously Variable Valve Timing Control System (CVTCS), adjusts the timing of the intake valves based on engine speed and load. At low speeds, VVT can advance the timing to improve low-end torque and reduce fuel consumption. At higher speeds, it can retard the timing to maximize horsepower.

The 2006 G35 was available in both rear-wheel drive (RWD) and all-wheel drive (AWD) configurations, with either a 5-speed automatic or a 6-speed manual transmission. The drivetrain significantly impacts fuel economy. AWD models, due to the added weight and friction of the additional components, generally experience lower gas mileage compared to their RWD counterparts. The type of transmission also plays a role; while modern automatics can be very efficient, the older 5-speed automatic in the 2006 G35 might not be as fuel-efficient as a modern CVT or dual-clutch transmission.

Factory Fuel Economy Ratings

According to the EPA, the 2006 Infiniti G35 RWD with the automatic transmission was rated at approximately 19 mpg city and 26 mpg highway. The manual transmission version was rated slightly lower. The AWD models typically had ratings around 18 mpg city and 24 mpg highway. These figures serve as a baseline, but real-world gas mileage can vary significantly based on driving habits, vehicle condition, and environmental factors.

Factors Affecting Fuel Economy

Several factors can contribute to deviations from the factory fuel economy ratings. Identifying and addressing these factors can help improve the fuel efficiency of your 2006 G35.

Driving Habits: Aggressive acceleration, hard braking, and high-speed cruising consume significantly more fuel. Smooth, consistent driving at moderate speeds is crucial for maximizing gas mileage.
Vehicle Maintenance: Neglecting routine maintenance can lead to decreased fuel efficiency. Key maintenance items include:
- Air Filter: A clogged air filter restricts airflow to the engine, causing it to work harder and consume more fuel.
- Spark Plugs: Worn or fouled spark plugs can result in incomplete combustion, reducing power and increasing fuel consumption. Replace spark plugs at the recommended intervals.
- Fuel Filter: A clogged fuel filter restricts fuel flow, potentially causing the engine to run lean and reduce fuel economy.
- Tire Pressure: Underinflated tires increase rolling resistance, leading to higher fuel consumption. Maintain the recommended tire pressure.
- Engine Oil: Using the correct viscosity engine oil and changing it regularly helps reduce friction within the engine, improving efficiency.
- Oxygen Sensors (O2 Sensors): These sensors monitor the oxygen content in the exhaust and provide feedback to the engine control unit (ECU) to adjust the air-fuel mixture. Faulty O2 sensors can lead to incorrect air-fuel ratios and reduced fuel economy.
Vehicle Condition: Mechanical issues, such as vacuum leaks, worn suspension components, or dragging brakes, can negatively impact fuel economy.
Environmental Factors: Cold weather, hilly terrain, and heavy traffic can all increase fuel consumption.
Fuel Quality: Using lower-octane fuel than recommended can reduce engine performance and fuel economy. The 2006 G35 is designed to run on premium fuel (91 octane or higher) for optimal performance and efficiency.
Modifications: Aftermarket modifications, such as larger wheels and tires, performance exhaust systems, and engine tuning, can alter the engine's performance characteristics and affect fuel economy.

Troubleshooting Poor Fuel Economy

If you're experiencing significantly lower fuel economy than expected, consider the following troubleshooting steps:

Check for Obvious Issues: Look for signs of leaks (fuel, oil, coolant), unusual noises, or warning lights on the dashboard.
Scan for Diagnostic Trouble Codes (DTCs): Use an OBD-II scanner to check for any stored DTCs. These codes can provide valuable clues about potential problems. Common codes related to fuel economy include those related to O2 sensors, mass airflow (MAF) sensor, and fuel trim.
Inspect the Air Filter: Remove the air filter and visually inspect it for dirt and debris. Replace it if necessary.
Check Tire Pressure: Ensure that all tires are inflated to the recommended pressure.
Monitor Fuel Trims: Using an OBD-II scanner, monitor the short-term and long-term fuel trims. High positive or negative fuel trims can indicate a vacuum leak, faulty O2 sensor, or other issues affecting the air-fuel mixture. Fuel trim is the ECU's adjustment to the air-fuel mixture based on feedback from the O2 sensors.
Inspect for Vacuum Leaks: Use a vacuum gauge or smoke machine to check for vacuum leaks. Common leak locations include intake manifold gaskets, vacuum hoses, and throttle body gaskets.
Evaluate O2 Sensor Performance: Use an OBD-II scanner to monitor the O2 sensor readings. The sensors should switch between rich and lean conditions. Slow or erratic readings can indicate a faulty sensor.
Check the Mass Airflow (MAF) Sensor: A dirty or faulty MAF sensor can provide inaccurate airflow readings to the ECU, leading to incorrect air-fuel ratios. Clean the MAF sensor with a MAF sensor cleaner. Be very careful not to damage the delicate sensor wires.
Evaluate Fuel Injector Performance: Consider having the fuel injectors professionally cleaned and tested to ensure they are delivering fuel properly.

Modifications and Fuel Economy

Many owners modify their 2006 G35s for increased performance or aesthetics. However, it's important to understand that these modifications can often impact fuel economy.

Intake and Exhaust Modifications: While aftermarket intakes and exhaust systems can improve airflow and increase horsepower, they may also alter the engine's fuel mapping and potentially reduce fuel efficiency if not properly tuned.
Engine Tuning: Custom engine tuning can optimize the air-fuel ratio and ignition timing for improved performance, but it can also negatively impact fuel economy if not done carefully. A proper tune will optimize for both power and efficiency, but aggressive tunes prioritizing power may sacrifice fuel economy.
Wheels and Tires: Larger wheels and tires, especially those with wider contact patches, can increase rolling resistance and reduce fuel economy. Heavier wheels also require more energy to accelerate, further impacting fuel efficiency.
Suspension Modifications: Lowering the suspension can improve aerodynamics, but it can also affect the alignment and potentially increase rolling resistance if not properly aligned.

Conclusion

The fuel economy of a 2006 Infiniti G35 depends on a variety of factors, including driving habits, vehicle maintenance, and environmental conditions. By understanding these factors and performing regular maintenance, you can optimize the fuel efficiency of your G35. If you're experiencing poor fuel economy, systematically troubleshoot the potential causes and address any underlying issues. Remember that modifications can impact fuel economy, so choose your upgrades wisely and consider their potential effects on your G35's overall efficiency. While the 2006 G35 offers a sporty driving experience, with proper care and attention, it can also deliver reasonable fuel economy for its class.

Always consult a qualified mechanic if you are unsure about any repairs or troubleshooting procedures.