Subaru produces a water-cooled, front-mounted flat-four engine marketed as "H-4", meaning "horizontal" rather than the "H" cross-section normally indicated by an "H engine". Subaru has created a number of engines, starting with the EA series introduced in 1966, progressing towards the currently used EJ series, which is wide but very short and light, and is mounted ahead of the front axle with the transmission behind. With this layout, the gearbox can remain very similar to common transmissions in both design and weight without the need for a bulky and inefficient transfer case.[6] Although it is more expensive than a straight-four, it allows Subaru to build an all-wheel drive vehicle at little extra cost from two-wheel drive.[6]