Subaru is one of the few automakers that didn't suffer much during the Great Recession a few years ago, and today its sales are still through the roof. Basically, production can't keep up with demand and brand new models like the Forester and Legacy don't stay on dealerships lots for long. So what's the secret to Subaru's success? Several things, and one of them is no doubt its horizontally-opposed "Boxer" engine. Funnily enough, not all Subaru buyers are aware of this unique engine design.

And yet Subaru is now celebrating its 50th anniversary of Boxer engine production. The first Boxer-powered Subie was the 1000 compact passenger car that debuted on May 14, 1966. Today, every Subaru is fitted with a Boxer engine, with total production over the past 50 years now numbering over 16 million units. So what is a horizontally-opposed "Boxer" engine, exactly? Basically, the pistons face each other in a side-to-side symmetrical layout. The opposing pistons work to cancel out the inertia force of each other, resulting in less vibration and better rotational balance which provides a smoother feel right up to the high rev range. The other Subaru essential is, of course, all-wheel drive (the BRZ is the sole exception). Here's to the next 50 years, Subaru.

You can also check out Subaru compact car models.