Fuel Efficiency and Emissions Are Hurting Engine Reliability

Key Points

• Smaller, more powerful and fuel-efficient engines don’t seem to have great long term reliability. 
• Engine recalls from major automakers such as GM, Toyota and Honda have cost billions of dollars. 
• Moves to make engines more efficient while maintaining power, such as thinner engine oil, seem to be the culprit. 

Modern car engine technology is probably the best it’s ever been, with engines getting smaller and more efficient while maintaining output levels of bigger power plants. Unfortunately, this progress comes with a trade-off: reliability. Vehicle recalls have been high for the last few years; according to the National Highway Traffic Safety Administration, there were over 29 million vehicles recalled in 2024, with 2025 recall levels shaping up to be as much or slightly more. A major focus of the recalls are engines: Per Automotive News, there are currently over 5 million engines from five major automakers that are either under recall or facing more serious investigations. 

Related: Toyota Again Tops Consumer Reports Annual Auto Reliability Survey

Fuel Efficiency Seems to Be Hurting Long-Term Reliability

• Takeaway: The technology that has allowed engines to become smaller, more efficient and make horsepower similar to larger engines seems to be one of the main reasons so many engines are being recalled.

Stricter fuel-economy standards backed automakers into a wall. How were they supposed to deliver engines that are efficient while maintaining the power that many customers demand? Automakers responded by turbocharging engines or more commonly implementing direct fuel injection. The results were engines that could deliver hybrid-rivaling fuel economy, such as Hyundai’s naturally aspirated 2.5-liter four-cylinder that delivers over 30 mpg combined in the Sonata; small three- and four-cylinder engines can also deliver impressive fuel economy and make power comparable to V-6 and V-8 engines from 20 and 30 years ago, such as Ford’s 315-hp EcoBoost four-cylinder for the Mustang and Toyota’s high-performance 300-hp, turbo three-cylinder that powers the GR Corolla. 

While these engines may be the stuff of automotive engineers’ dreams, that power and efficiency comes at the cost of reliability. Simply put, these modern engines are too high-strung and running too hot. Automotive News spoke with industry experts who said that the power and high temperatures these engines are running at are putting considerable stress on critical engine components. Compounding things is the use of thinner engine oil, which also aids in increasing fuel economy and horsepower. 

This thin engine oil is also affecting engines that have historically had great reliability. In April, GM issued a recall for nearly 600,000 vehicles powered by its 6.2-liter V-8 in the U.S., including the Chevrolet Silverado 1500 pickup truck and Cadillac Escalade SUV, for engine failure. NHTSA also opened an investigation for another 286,000 vehicles in late October. GM has said it expects 3% of these engines to fail dealer diagnostic tests. Those vehicles that have their engines fail the test will receive new engines; engines that pass will receive thicker engine oil. 

What Automakers Are Saying

• Takeaway: Automakers aren’t saying much about these recalls for obvious reasons, but they remain committed to making things right for those owners who have been affected by them. 

Recalls, especially ones surrounding powertrains, aren’t great topics for automakers. We reached out to GM, Honda and Toyota to see how they’re handling things. GM didn’t respond, though we’ll update this post if it gets back to us. Toyota spokesperson Jacob Brown sent a statement saying where owners could find information regarding the recalls and briefly described the problems going on with the recalled V-6 engines:

“There is a possibility that certain machining debris may not have been cleared from the engine when it was produced,” he said. “In the involved vehicles, this can lead to potential engine knocking, engine rough running, engine no-start and/or a loss of motive power. A loss of motive power while driving at higher speeds can increase the risk of a crash.”

Honda spokesperson Jake Berg more or less said the same thing, stating the automaker is committed to owner safety and detailing where owners can go to find resources for recall help and information:

“In November 2023, American Honda recalled approximately 250,000 vehicles across multiple models for a recognized connecting rod defect, and the majority of vehicles included in this recall have already been repaired.”

Engine Recalls Are a Pricey, Time-Consuming Headache

• Takeaway: Recalls are costing automakers billions, hurting dealer profits and inconveniencing consumers.

Millions of engines under recall are spreading the hurt around to automakers, consumers and dealerships, with automakers set to spend hundreds of millions of dollars on engine-related recalls for 2025. Per Automotive News, current major engine recalls include:

• Ford: Over 700,000 Ford engines are under recall for failures that could ultimately result in engine fires. It’s not known how much these recalls will cost Ford.
• Honda: Nearly a quarter of a million V-6 engines from Honda have been recalled for engine failure, and another 1.4 million engines were added to the recall after a NHTSA investigation. It’s also not known how much the recall will cost the automaker.
• Hyundai: Over 3 million of Hyundai’s Theta II, Gamma and Nu engine lines have been recalled, affecting models going back over a decade. A slew of lawsuits, settlements and fines means that Hyundai could eventually pay out over $5 billion because of the recall.
• Stellantis: Over 120,000 2023-25 Jeeps have been recalled over engine failures. The recall could cost the automaker $500 million.
• Toyota: Some 229,000 of Toyota’s twin-turbo hybrid V-6 engines are under recall due to debris in the engine block that can cause engine failure. The automaker is expected to pay over $1 billion after everything is said and done.

If an engine failure results in the automaker approving a full replacement, it is a time-consuming affair that ultimately disrupts customer lives. For instance, replacement of Toyota’s hybrid V-6 can take anywhere from 13-21 hours, pulling experienced dealer techs away from other services. 

How These Recalls Affect Overall Brand Reliability

Takeaways:

• Overall reliability ratings for some brands don’t seem to be affected by these massive recalls, likely due to the reliability of other models in their lineups.
• Other brands have poor overall ratings, likely because of the amount of recalls they’ve had.

So, how do these recalls affect the overall reliability of the brands? It depends, according to reliability data from Consumer Reports. For instance, Toyota is ranked No. 1 when it comes to new-car reliability, but its least reliable new vehicle is the Tundra pickup truck, whose hybrid V-6 engine is, as mentioned above, facing a recall. For used-car reliability, Toyota is ranked second behind its luxury brand, Lexus. The fact that the brand is ranked high despite its major engine recall suggests the overall reliability of models like the Camry, Corolla and 4Runner, the latter of which is its most reliable new model, help Toyota’s rating.

In another example of the variability of these ratings, Honda is No. 4 in both new and used reliability. Like Toyota, the reliability of other models in Honda’s lineup seems to be helping the brand, as well as the fact that the recall of its V-6 engine mainly affects older models.

Ford is ranked No. 11 for new-vehicle reliability and No. 19 for used-car reliability. Both rankings likely have something to do with the massive number of recalls the automaker has had in 2025. Meanwhile, Hyundai’s Nos. 12 and 17 rankings for new and used reliability, respectively, seem to be a reflection of the ongoing saga of engine recalls its owners have been dealing with for oil consumption issues.

Jeep, on the other hand, seems to be an outlier — and not necessarily in a good way. The brand is No. 24 out of 26 for new-vehicle reliability (its worst vehicle’s reliability, the Grand Cherokee 4xe, we can personally attest to) and second from the bottom for used-vehicle reliability.

The same can be said for GM’s Chevrolet, Cadillac and GMC brands. Their lower rankings on both the new (Nos. 17, 18 and 23 place, respectively) and used (Cadillac is No. 16, Chevrolet No. 18 and GMC No. 22) reliability lists could be a reflection of the over half million 6.2-liter V-8-powered models currently under recall.

What can a consumer do? Just be careful and do your due diligence when buying a car. If you’re in the market for one of these vehicles (or any vehicle, for that matter) with an engine recall, make sure to request a vehicle history report to see whether or not a recall fix has been performed on the car. Or you can have an independent mechanic check the vehicle out for you, something that can usually be negotiated on when buying a vehicle. In the end, it’s the owner of the car that’s affected most. Be it a commuter who needs their vehicle to get to work or a contractor who needs their truck for their livelihood, engine unreliability has repercussions that can affect everyone.

Editor’s note: This story was updated Dec. 10, 2025, with additional information from Consumer Reports on brand reliability and a correction that Hyundai’s naturally aspirated 2.5-liter four-cylinder engine is equipped in the Sonata.

Read More News on Fuel Efficiency and Reliability:

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• Fuel-Economy Standards May Get Rolled Back to 34.5 MPG by 2031
• What Are the Most Reliable Cars and Brands?
• Are Electric Cars Better for the Environment?
• What Are the Most Fuel-Efficient Cars?

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