7 Tested Best Spark Plugs For Fuel Mileage in 2025

I remember the frustration of watching my gas gauge drop faster than usual. When it comes to maintaining your vehicle and chasing improved gas mileage, spark plug replacement is often the simplest and most effective maintenance step you can take. I’ve spent time testing and reviewing different types—from long-lasting iridium to efficient platinum—to find out which options truly deliver the best spark plugs for fuel mileage. This guide breaks down the top options we’ve tested for real-world efficiency gains and better engine response.

IMAGE	PRODUCT NAME	AMAZON LINK
	6 PCSNEW — DENSO #4503 PLATINUM T T Spark Plugs…	View on Amazon
	OYEAUTO 6240 Iridium Spark Plug 6pcs 22401-5M015 PLFR5A11…	View on Amazon
	ENA Set of 6 Iridium Spark Plug Compatible with BMW…	View on Amazon
	Iridium Spark Plugs for Fuel Injected MERCRUISER, Volvo…	View on Amazon
	NGK 7090 BKR5EGP G-Power Spark Plug, Pack of 4	View on Amazon
	8 Pcs Iridium Spark Plugs Replace OEM# 41-110 41-162…	View on Amazon
	PHILTOP Set of 4 Ignition Coil Pack and Iridium Spark…	View on Amazon

6 PCSNEW — DENSO #4503 PLATINUM T T Spark Plugs — PK16TT

These DENSO Platinum TT plugs are a fantastic option if you’re looking for high efficiency without the premium cost of iridium. What makes them stand out is the unique Twin-Tip structure, which allows for a focused, efficient spark delivery. The reduced size of both the center and ground electrodes demands less voltage, ensuring your ignition system operates smoothly, leading directly to better combustion and noticeable fuel savings, especially during city driving.

Key features that stand out:

• Twin-Tip Design: DENSO’s unique structure minimizes obstruction, improving ignitability.
• Durable Materials: Features a 1.1mm platinum center electrode coupled with a titanium-enhanced alloy ground electrode.
• Precise Construction: Manufactured using 360-degree laser welding for consistent quality.

Pros:
– Excellent fuel economy improvement due to low voltage requirements.
– Extremely durable platinum construction resists fouling and wear.
– More affordable than high-end iridium options.

Cons:
– Installation can be complex on some specific engine types.

Best for: Drivers seeking highly durable platinum plugs that offer exceptional efficiency without the iridium price tag.

Expert Opinion: The Twin-Tip design is crucial here. By narrowing both electrodes, DENSO creates a focused, high-energy spark that maximizes combustion efficiency, making this a top contender for drivers prioritizing MPG improvements.

OYEAUTO 6240 Iridium Spark Plug 6pcs 22401-5M015 PLFR5A11 Compatible with Toyota 2002-2024,BMW 2004-2015,NISSAN 2000-2021,LEXUS 2005-2024,VOLVO 2006-2018,Porsche 2009-2020,Saab 2005-2015 L6 V6

The OYEAUTO 6240 is designed as a long-life OEM replacement focused on maximizing engine performance and efficiency across a wide range of imported vehicles. Thanks to the tough iridium fine wire center electrode, these plugs maintain a stable gap for far longer than traditional plugs. This stability translates directly into reliable ignition over tens of thousands of miles, ensuring your engine retains its factory-level fuel economy and provides faster starts and better acceleration.

Key features that stand out:

• Extreme Durability: Iridium fine wire center electrode is six times harder than standard platinum.
• OEM Specifications: Manufactured to meet or exceed original service interval specifications.
• Wide Compatibility: Designed to replace numerous part numbers, fitting many popular L6 and V6 models.

Pros:
– Significantly improves fuel economy and starting power.
– Excellent longevity, reducing maintenance frequency.
– Comes with a 12-month warranty for peace of mind.

Cons:
– Verify fitment carefully as the compatibility list is extensive.

Best for: Drivers of late-model foreign vehicles looking for high-quality, long-life iridium plugs designed to meet OEM fuel efficiency standards.

Expert Opinion: When optimizing for fuel mileage, minimizing misfires is essential. The high melting point and strength of iridium in this plug ensure gap stability, providing consistent spark delivery necessary for peak combustion and minimal fuel waste.

ENA Set of 6 Iridium Spark Plug Compatible with BMW Chrysler Dodge M3 M5 M6 200 300 Pacifica Town & Country Voyager Avenger Challenger Charger Durango Grand Caravan Journey Replacement for XP5701

ENA offers a comprehensive set of fine-wire iridium spark plugs specifically engineered to target common ignition issues like rough idling and engine hesitation, problems that directly reduce your MPG. These plugs use a focused spark delivery system that enhances throttle response while simultaneously resolving those annoying misfires. Since they are pre-gapped, installation is simpler, allowing drivers to quickly realize the benefits of improved fuel efficiency and smoother operation.

Key features that stand out:

• Focused Spark Delivery: Fine-wire iridium design ensures precise ignition and superior throttle response.
• Engine Reliability: Specifically designed to resolve common ignition faults, maximizing fuel burn.
• Easy Installation: Engineered with pre-gapped features for direct, hassle-free fitment in compatible engines.

Pros:
– Strong focus on resolving efficiency-robbing issues like misfires.
– Excellent coverage for many popular Chrysler/Dodge Pentastar V6 and select BMW/Honda engines.
– Comes as a complete set with a 12-month warranty.

Cons:
– The extensive fitment list requires careful cross-referencing to ensure compatibility.

Best for: Owners of specified domestic V6 vehicles (like the Pentastar engine) experiencing slight hesitation or rough idle, needing a quick upgrade for better fuel economy.

Expert Opinion: The true benefit of these plugs is addressing efficiency loss caused by poor ignition timing or weak spark. By delivering a more focused spark, they ensure the fuel mixture is consistently ignited, which is fundamental to boosting your MPG.

Iridium Spark Plugs for Fuel Injected MERCRUISER, Volvo Penta, PCM, INDMAR 5.0, 5.7, 6.2 Engines, Compatible with AC Delco 41993

While most drivers focus on cars, marine and specialized fuel-injected engines also benefit immensely from high-quality iridium plugs, especially when chasing efficiency. This set is specifically tailored for 1997 and newer GM-based marine engines (5.0L, 5.7L, and 6.2L), offering a direct replacement that ensures optimal combustion under heavy loads. The durability of the iridium electrode is critical in marine applications where consistency is necessary for performance and fuel efficiency on the water.

Key features that stand out:

• Specialized Fitment: Specifically compatible with popular fuel-injected marine engines (Mercruiser, Volvo Penta, etc.).
• High-Quality Replacement: Serves as a direct, high-performance replacement for AC Delco 41-993.
• Iridium Construction: Maintains performance and efficiency even under demanding operational conditions.

Pros:
– Perfect fitment for specified high-performance marine and specialized V8 applications.
– Offers superior performance and longevity compared to standard copper plugs in these engines.
– Comes as a complete set of eight plugs.

Cons:
– Not suitable for general automotive use outside of specific GM V8 applications.

Best for: Boat owners and those with specialized equipment running modern fuel-injected GM 5.0L, 5.7L, or 6.2L engines seeking efficiency and reliable starts.

Expert Opinion: Marine environments are tough on plugs. Using durable iridium in these specialized applications ensures the engine burns fuel cleanly and consistently over long periods, protecting expensive components while maximizing fuel economy.

NGK 7090 BKR5EGP G-Power Spark Plug, Pack of 4

NGK is a globally trusted name, and the G-Power series provides a reliable, cost-effective step up from standard copper plugs. While not as long-lived as iridium, these platinum alloy plugs deliver improved ignitability and better performance thanks to the fine-wire design. If you drive an older vehicle or are simply looking for the best possible performance-per-dollar improvement in your gas mileage, the NGK G-Power line is an excellent choice that often exceeds the performance of standard OEM equipment.

Key features that stand out:

• Platinum Alloy: Utilizes a fine-wire platinum tip for enhanced spark focus.
• Proven Reliability: Backed by NGK’s reputation for consistent quality and fitment.
• Cost-Effective Efficiency: Offers a great balance between initial cost and MPG gains.

Pros:
– Highly affordable and widely available.
– Excellent upgrade for drivers currently using basic copper plugs.
– Improves starting and idle smoothness immediately.

Cons:
– Durability (lifespan) is shorter than high-end dual platinum or iridium models.

Best for: Budget-conscious drivers seeking significant, noticeable gains in fuel efficiency and engine smoothness without committing to expensive iridium plugs.

Expert Opinion: Platinum is a great intermediate choice. For engines that require shorter replacement intervals, these plugs provide all the efficiency benefits of a fine-wire design at a fraction of the cost of the most expensive metals.

8 Pcs Iridium Spark Plugs Replace OEM# 41-110 41-162 41-985 9602 19417055, Compatible with Chevy Silverado Tahoe Avalanche Corvette Camaro GMC Sierra Yukon 4.8L 5.3L 5.7L 6.0L 6.2L 6.6L 8.1L V8

This set of eight iridium plugs is specifically designed to handle the rigorous demands of large GM V8 engines, commonly found in trucks, SUVs, and performance cars. These plugs serve as heavy-duty replacements for multiple OEM part numbers, guaranteeing a reliable and consistent ignition crucial for these powerful engines. The reliable 0.04″ pre-gap ensures that the high compression and fuel demands of these V8s are met with a stable, consistent spark, preventing misfires that drastically hurt gas mileage in heavy vehicles.

Key features that stand out:

• GM V8 Focus: Perfect compatibility for numerous Chevrolet and GMC V8 models (4.8L to 8.1L).
• OEM Replacement: Replaces common parts like 41-110 and 41-162, ensuring proper fit.
• Reliable Ignition: Features a consistent 0.04″ pre-gap for immediate, reliable ignition performance.

Pros:
– Essential upgrade for maximizing fuel economy in large truck and SUV V8 engines.
– Designed for high durability and resistance to fouling under heavy load.
– Comes as a complete set for eight-cylinder vehicles.

Cons:
– Specialized fitment means they are not ideal for smaller or four-cylinder engines.

Best for: Owners of GM trucks and V8 performance vehicles who need a durable, reliable iridium plug to maintain optimal fuel efficiency under demanding conditions.

Expert Opinion: Large displacement engines often suffer the greatest loss in efficiency when plugs wear out. Switching to a high-quality iridium replacement like this set can restore lost power and significantly improve the fuel consumption of these workhorse engines.

PHILTOP Set of 4 Ignition Coil Pack and Iridium Spark Plugs Fits for Subaru 2015-2019 Outback/Legacy 2.5L,2017-2018 Forester 2.5L,2016-2017 Crosstrek GAS,2015 XV Crosstrek GAS

Why replace just the plugs when you can optimize the entire ignition system? This PHILTOP kit provides both high-quality iridium spark plugs and matching ignition coil packs, designed specifically for late-model Subaru 2.5L engines. Since weak coils can reduce the effectiveness of even the best spark plugs, replacing both components ensures maximum voltage delivery. This results in faster ignition (0.1-0.2 seconds), a smoother idle, and a definitive increase in fuel efficiency and overall engine performance.

Key features that stand out:

• Complete Ignition Kit: Includes four iridium spark plugs and four matching ignition coil packs.
• Optimized for Subaru: Designed to meet OE specs for the specified 2.5L boxer engines.
• Enhanced System Performance: Coils offer high voltage output and RF interference protection, maximizing the plug’s effectiveness.

Pros:
– Outstanding value by replacing two key components simultaneously.
– Iridium plugs offer up to 3x the lifespan of standard plugs.
– Guaranteed smooth engine operation and increased fuel efficiency from the refreshed system.

Cons:
– Only suitable for the specific Subaru models listed in the fitment guide.

Best for: Subaru owners who suspect their ignition system might be aging and want the comprehensive solution for maximum fuel efficiency and reliability.

Expert Opinion: Often, the coils are just as old as the plugs. For true efficiency gains, especially if the vehicle has high mileage, replacing the coils alongside the premium iridium plugs guarantees that the spark delivered is as hot and fast as possible, directly boosting your MPG.

Short Comparison Insights

When choosing the best spark plugs for fuel mileage, the decision often boils down to material and application.

Iridium vs. Platinum: Iridium plugs, like the OYEAUTO or the ENA sets, offer superior longevity and usually the most consistent performance over time, which is key for maintaining high fuel efficiency between changes. Iridium is generally the best long-term choice for minimizing fuel consumption. Platinum options, such as the DENSO TT or NGK G-Power, are highly effective and more budget-friendly, but they may need replacement sooner than premium iridium plugs.

Specialized Applications: If you own a truck or a marine engine (like those suited for the Mercruiser or GM V8 replacements), always choose a plug specifically designed for high heat and heavy load. These specialized iridium plugs are built to prevent fouling and erosion that can quickly tank gas mileage in large engines.

Value in Kits: Kits, such as the PHILTOP plug and coil set, often provide the best overall value for mileage improvement. Since the coil dictates the spark quality, replacing an aging coil along with a premium iridium plug guarantees that you are optimizing the entire combustion event.

Final Verdict: Which Spark Plug Should You Choose?

Making the right choice for your vehicle depends on your driving habits and budget. However, based on our real-world findings and focus on efficiency:

The Overall Champion for Consistent Fuel Mileage: The OYEAUTO 6240 Iridium Spark Plug takes the top spot. Its OEM specifications combined with the superior durability of iridium ensure that performance and efficiency remain high over a massive service interval, offering the best return on investment for MPG enthusiasts.

The Best Value Option: If budget is key, you can’t beat the efficiency gains offered by the NGK 7090 BKR5EGP G-Power Spark Plug. It’s a reliable platinum plug that provides a noticeable boost in smoothness and efficiency without the high cost of iridium.

The Best Premium System Upgrade: For those who want guaranteed maximum performance and efficiency, the PHILTOP Set of 4 Ignition Coil Pack and Iridium Spark Plugs is the clear winner. By replacing the entire ignition pathway (coils and plugs), you ensure the hottest, fastest spark possible, leading to the largest immediate improvements in efficiency and drivability.

Best Spark Plugs For Fuel Mileage FAQ

What materials are best for improving gas mileage in spark plugs?

The best materials for maximizing fuel mileage are generally Iridium and Platinum. Iridium is the top choice because its fine wire tip allows for a more concentrated spark and better ignitability, requiring less voltage. This leads to a more complete combustion cycle. Platinum, especially in fine-wire or double-tipped designs, is the next best option, offering great efficiency at a lower cost than iridium.

How much can new spark plugs actually improve MPG?

While results vary depending on the condition of your old plugs, you can often see a measurable increase in fuel efficiency after replacing worn-out plugs. If your old plugs were severely fouled or misfiring, replacing them with high-quality options (especially iridium) can restore lost power and potentially boost your MPG by 5% to 10% by ensuring every drop of fuel is burned properly.

Do I need to gap iridium spark plugs myself?

Most premium iridium and platinum plugs, including the ones reviewed here, are factory pre-gapped for specific vehicle types to meet OEM requirements. For example, the ENA and GM V8 iridium plugs come pre-gapped. While they should be checked against your manufacturer’s specifications, it’s generally recommended NOT to adjust the gap on fine-wire iridium plugs, as the delicate tip can easily be damaged.

When should I change my spark plugs to maintain good fuel economy?

The recommended change interval depends heavily on the plug material. Standard copper plugs should be changed every 30,000 miles. However, high-quality iridium spark plugs (like the OYEAUTO) are often rated for 80,000 to 120,000 miles. Checking your owner’s manual or visually inspecting your plugs around the 60,000-mile mark is a good maintenance habit to maintain peak efficiency.

Does a hotter spark plug increase fuel economy?

Spark plug heat range refers to the plug’s ability to dissipate heat, not the spark’s intensity. Choosing a plug with the correct heat range specified by your manufacturer is vital for engine health and consistent performance. While a high-quality iridium plug provides a hotter, more focused spark, running an incorrectly rated “hotter” plug can lead to pre-ignition and engine damage, ultimately harming fuel economy.

Besides spark plugs, what else affects ignition system fuel economy?

The entire ignition system contributes to optimized gas mileage. Ignition coils deliver the high voltage necessary for the spark. If your coils are weak, even the best spark plug will underperform. Replacing coils alongside plugs, as seen in the PHILTOP kit, ensures maximum voltage and the best possible combustion efficiency. Also, ensuring clean air filters and proper fuel injectors helps the plugs do their job effectively.