Fuji Heavy Industries, the maker of Subaru vehicles in Japan, introduced the world's first Horizontally-Opposed Diesel Engine 'Subaru Boxer Diesel' for passenger vehicles. Subaru Europe first launched the engine, fitted on the Legacy and Outback models, in January 2008. The 2.0 flat-four turbo diesel is mated with Subaru's unique symmetrical AWD (All-Wheel-Drive) to achieve driving performance only Subaru is capable of. This provides high-level driving stability and outstanding acceleration thanks to powerful low- and medium-speed torque. The Subaru Boxer Diesel takes advantage of high rigidity of the horizontally opposed engine. It uses an aluminum-alloy cylinder block.

With its engine width equivalent to that of a horizontally opposed petrol engine of the same displacement volume, it is 61.3-mm shorter in length, achieving top-level lightweight and the most compact design in its the class. Its unique layout allows the right and left pistons to negate each other's inertia and to realize a smooth rotational balance, achieving low vibration and superior quietness. With its outstanding acceleration response, the Subaru Boxer Diesel features engine characteristics worth the name of a sports diesel. This unique engine has been making headlines in the automotive press as a true technological breakthrough. It is still receiving extensive coverage in specialized engineering papers. The 2.0 Boxer Diesel engine is currently available on the Legacy, Outback, Forester and Impreza models.