General Motors is back in legal hot water—this time over a fix that may have done more harm than good. A new class-action lawsuit claims GM tackled a nagging engine ticking issue by rolling out a factory repair that ended up guzzling gas instead.
At the heart of the dispute is the 6.2-liter V8 engine found in several popular GM vehicles. According to the lawsuit, the recall fix disables the engine’s Dynamic Fuel Management (DFM) system, which normally switches between V4 and V8 modes to save fuel. With DFM stuck in full-time V8, drivers say their mileage has taken a serious hit.
Filed in a Michigan district court, the suit accuses GM of masking one issue while quietly creating another—leaving owners with quieter engines, but lighter wallets at the pump.
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Last year, GM issued a Technical Service Bulletin that seemed straightforward enough: to fix ticking noises and performance quirks in its 6.2-liter V8, dealerships were told to disable the Dynamic Fuel Management system. This engine powers a wide range of best-sellers, including the Chevy Silverado, GMC Sierra, and Cadillac Escalade.
But what looked like a simple tweak may have come with a hidden price. According to the new lawsuit, owners say they were never warned that the fix would permanently kill off cylinder deactivation—and with it, 2 to 4 miles per gallon.
Now, those same drivers are left with trucks that burn more fuel than before, and no way to turn the system back on. They’re arguing GM should’ve been a lot more transparent about what they were really giving up.
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What Looked Like a Fix, Felt More Like a Trade-off
The 6.2-liter V8 has earned a solid fanbase for delivering the kind of power you’d expect from a big engine—without crushing you at the gas pump. That’s mostly thanks to GM’s Dynamic Fuel Management system, which cleverly lets the engine run on fewer cylinders when you don’t need the full muscle.
It was smart tech that made the engine feel like a win-win: big performance when you want it, better mileage when you don’t. But then came the complaints—engine ticking, hesitation, and overall rough behavior—that pushed GM to roll out a software fix.
That “fix,” owners now say, quietly disabled the very system that made the engine efficient in the first place. Suddenly, they’re stuck in full V8 mode with no heads-up that their fuel economy would take a hit.
“Thicker oil may (or may not) help mitigate the engine defect, but it will also materially decrease fuel economy and require owners to purchase hundreds of extra gallons of gasoline over their vehicles’ lifespans,” the suit says. “Thus, as the result of the underlying defect and GM’s recall remedy, owners are presented with two bad options: do nothing and risk catastrophic engine failure or get the recall and pay hundreds of dollars more for gasoline.”
One Escalade owner in the lawsuit says his highway mileage nosedived from 21 to 17 mpg after the update. That might not sound huge at first—but over time, it adds up to hundreds more at the pump every year.
For a fix that was supposed to make things better, he says it’s turned into a pricey downgrade.
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GM Is Silent So Far, but the Fallout Could Be Big
GM hasn’t said anything publicly about the lawsuit yet, but legal experts say the case could have some serious ripple effects. At the center of it all is a big question: Can an automaker push out a software update that permanently shuts down a key feature—without giving owners a say?
The plaintiffs argue they were never told what they’d be giving up, and they definitely weren’t offered a way to undo the change. To them, better fuel economy wasn’t just a perk—it was part of the pitch.
If the class action gains traction, it could pave the way for thousands of GM owners to ask for compensation—or for GM to bring back the fuel-saving tech that quietly disappeared.
How-To Geek’s Take
GM’s V8 engines have landed in hot water before. Earlier versions of the 5.3-liter and 6.2-liter engines faced lawsuits over problems like burning too much oil, lifter failures, and timing glitches—many tied to that same cylinder deactivation tech.
Now, drivers of GM trucks and SUVs are stuck with lower gas mileage and a lot more questions than clear answers.
