TOKYO — As part of the Subaru Boxer’s 40th birthday party, parent Fuji Heavy Industries confirmed on Tuesday that the company is “in the final stages of developing a diesel boxer for launch within the next three years.”

The Japanese company reaffirmed its philosophy on boxer engines, saying they are “an integral part of Subaru’s future plans.”

Fuji Heavy Industries, the maker of Subarus, introduced the boxer in 1966 in the Subaru 1000, a sedan with a one-liter, four-cylinder engine and front-wheel drive. The company said, “Initially the flat-4 engine was considered quirky, but it paved the way for the symmetrical all-wheel-drive system.”

The horizontally opposed engines are called “boxer” because the cylinders are positioned sideways, with pumping action that resembles the punching motions of a boxer.

The engine powers the current Impreza WRX, Forester XT and Legacy GT.

What this means to you: Your next boxer engine may be a diesel.