Do Twin Turbos Help Or Hurt Your Gas Mileage?

The quick and short answer to whether twin turbos hurt gas mileage is no. As for whether they help with efficiency — again, the simple answer, mind you, is yes. As you may have imagined by now, things are pretty nuanced, with several variables at play. Put simply, the way you drive plays a large role – the whole process involves more than just the gas pedal, steering, and brakes. There's a lot of judgment, hand-eye coordination, and small calculations in the background that determine the outcome of the drive itself. Just like poor driving habits can cause transmission damage, they can also reduce your vehicle's fuel efficiency, whether your have twin turbos or not.

Turbocharging affects fuel efficiency, depending on usage, layout (single or twin), size, and so on. If you're sensible with the throttle pedal, expect decent fuel economy. On the other hand, if you drive the car like you stole it, turbocharging won't magically make the fuel gauge needle drop any slower.

Turbochargers, single or twin, are pretty straightforward in that they use exhaust gases to run turbines that help shove more air into the engine and burn more fuel. Ergo, you can get more horsepower without messing around with engine displacement. For the most part, turbo engines are better for gas mileage. However, their efficiency claims are not always true and feature several caveats. Allow us to explain.

Twin-turbocharged engines are typically reserved for high-end cars, owing to their complexity and added development costs. On the flipside, they allow for lighter and more compact engine designs without compromising on power. In fact, twin turbo engines offer 30% more power, sometimes even more, compared to naturally aspirated engines of similar size. Case in point, the now-discontinued Nissan GT-R came with a 3.8-liter twin-turbo V6 that offered 565 horsepower, whereas the V8-powered 2025 Ford Mustang pushes out just 486 horsepower from its naturally aspirated 5.0-liter engine.

Twin turbos, depending on how they are designed and arranged, have RPM levels (a rev range) where they operate at their peak and help the engine deliver its maximum output. For instance, a parallel twin-turbo setup (seen in the GT-R) features two turbochargers that operate as one large turbo, whereas a sequential arrangement uses twin turbos of varying sizes, each operating at different RPM levels. Whenever the turbos kick in, expect the engine to use more fuel. However, when the engine is not under boost — that is, when it's below, let's say, 3,000 RPM in the case of the GT-R — the engine is not making its full horsepower and is using much less fuel.

Essentially, when you're cruising around town, a twin-turbo engine will likely use less fuel, but when you're on it, don't expect much in terms of gas mileage. Of course, it depends on the engine, its power band, what gear you're in, your driving style, and so on. But the gist is, twin-turbocharged engines can be more fuel efficient than larger-capacity naturally aspirated engines, provided you're sensible with your right foot.