Subaru chose to continue their
longstanding use of the boxer engine in the Impreza. According to
Subaru, their configuration of the engine inline with the
transmission minimizes body roll due to the lower center of gravity
compared with offset engines in most other vehicles.
The Subaru layout is also
light-weight and lends itself easily to support all-wheel-drive,
with power delivered directly to the front and rear wheels, using an
integrated transfer case located inside the transmission. The boxer
design provides perfect vibration mitigation due to the fact that
the movement of each piston is exactly countered by the
corresponding piston in the opposing cylinder bank, eliminating the
need for a counter-rotating weighted crankshaft (harmonic balancer).
Torque steer is also reduced with this type of powertrain layout
since the front drive shafts are of equal length and weight.