Subaru as a whole makes reliable vehicles, but the Subaru Crosstrek is perhaps the most reliable. It also comes with a wide range of standard features, including all-wheel drive. And, for those after maximum fuel efficiency, there’s a plug-in hybrid version. However, despite the Crosstrek’s positive reviews, it has one big weak point: its lackluster standard engine. We’ve heard rumors that Subaru was working on a more powerful engine for the crossover. But recent news indicates, not only is it getting a larger engine option, it won’t be noticeably less fuel-efficient.

The 2021 Subaru Crosstrek’s new engine

In February 2020, Automotive News confirmed, courtesy of Subaru of America CEO Tom Doll, that the Subaru Crosstrek would receive a larger engine. As of this writing, the non-hybrid Crosstrek only offers a 2.0-liter flat-four engine rated at 152 hp and 145 lb-ft. To put that into perspective, my 1999 NB Miata makes only 12 less hp with its 1.8-liter four-cylinder.

But, for the 2021 model year, the Subaru Crosstrek will receive an optional 2.5-liter flat-four engine. As of this writing, Subaru has not confirmed how much power the engine will make. However, Motor Trend reports the Japanese automaker uses 2.5-liter engines in several other models, such as the Legacy and Outback. In those cars, it develops 182 hp and 176 lb-ft.

The power increase, though, isn’t the only news. MT and Autoblog report the EPA has published fuel economy ratings for the 2.5-liter engine. With the 2.0-liter and CVT, the Subaru Crosstrek is rated at 28 mpg city/33 mpg highway. In contrast, the 2.5-liter, which will likely be CVT-only, is rated at 27 mpg city/34 mpg highway. The 2.0-liter is available with a manual on lower trims, but it loses 5 mpg in both categories.

So, to summarize, the 2021 Subaru Crosstrek’s getting a bigger engine, and it seemingly won’t pay any efficiency penalties. Which, at first glance, seems unlikely. But there are some reasons for how this might be possible.

Dissecting the 2021 Subaru Crosstrek’s MPG claims

It’s worth noting that EPA ratings aren’t necessarily real-world accurate. For example, Car and Driver reported 32 mpg in its highway testing of a CVT-equipped Subaru Crosstrek. But, with the PHEV model, which is rated at 35 mpg on the highway, reviewers only saw 30 mpg.

However, as the Chicago Tribune explains, there may be a reason why the 2.5-liter is roughly as efficient as the 2.0-liter. A smaller engine has to rev higher than a larger engine to move the same car at the same speed. Say, just for example purposes, a 2.0-liter Subaru Crosstrek moving at 50 mph needs to be at 1800 RPM. In comparison, the 2.5-liter version at the same speed will be at 1500 RPM.

As RPMs rise, so do the friction forces within the engine. In addition, as Engineering Explained’s Jason Fenske explains, higher RPMs can shift engines out of their most-efficient operating area. Normally, a smaller engine burns less fuel than a larger one. But if the smaller engine’s spinning faster, it has to burn more fuel to make power and overcome friction. And depending on the size ratio between the engines, the RPM difference may be enough that these two factors balance out. E.g., the 2.0-liter has to spin so much faster than the 2.5-liter, it wipes out its natural efficiency advantage.

Availability and other updates

As of this writing, it’s unknown when the 2021 Subaru Crosstrek will go on sale. It’s also unknown how much the 2.5-liter engine will cost, and if it will increase the Crosstrek’s 1500-lb tow rating.

Car and Driver does report the engine will be available for the crossover’s Limited trim. In addition, the 2.5-liter will be optional for a new Sport trim. The current Subaru Crosstrek Limited starts at $27,395. The hybrid model, in comparison, starts at $35,145.

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