The 2018 Toyota Camry Hybrid is the most fuel-efficient version of all-new range of Toyota’s popular mid-size sedan, its best-selling vehicle in the U.S. until very recently.

The new Camry Hybrid is based on some of the same underpinnings as the 2016 Prius, and uses that car’s updated hybrid system and choice of two batteries.

In a car we judged to be more stylish than any previous hybrid Camry, the results are impressive.

It’s the first mid-size sedan ever rated by the EPA at more than 50 mpg combined: the 2018 Camry LE Hybrid comes in at 51 mpg city, 53 mpg highway, for a combined rating of 52 mpg.

We found the 2018 Camry Hybrid to be one of the two best-driving versions of the whole Camry lineup (along with the powerful but thirsty V-6 version) out of the five separate prototype 2018 Camry models we drove last month.

The Camry LE Hybrid achieves its high fuel-efficiency rating because it’s fitted with a lighter lithium-ion battery pack than the other two versions.

The heavier Camry SE Hybrid and Camry XLE Hybrid models use the older nickel-metal-hydride batteries that Toyota has long relied on.

They’re EPA-rated at 44 city, 47 highway, 46 mpg combined.

That’s still considerably better than the 32-mpg combined rating of the conventional Camry with a 2.5-liter 4-cylinder engine and a new 8-speed automatic transmission. (The bottom-line Camry L model comes in at 34 mpg combined, but it’s a stripped-down model mostly aimed at the taxi market and other fleet uses.)

Like the Prius, the battery pack of the Camry Hybrids now sits under the rear seat rather than in the trunk. That gives hybrid models the same 15.1 cubic feet of trunk space as any other Camry, along with a split folding rear seat back.

On the road, we found the new Camry Hybrid to be quiet and well-isolated except under maximum power demand, when a noticeable revving machinery noise comes from somewhere remote under the hood.

But the new generation of hybrid system frequently runs in electric-only mode at variety of speeds on flat roads, and when the engine switched on, it did so subtly enough that we sometimes didn’t notice.