  For a large class of inhomogeneous interacting particle systems (IPS) on a
lattice we develop a rigorous method for mapping them onto homogeneous IPS. Our
novel approach provides a direct way of obtaining the statistical properties of
such inhomogeneous systems by studying the far simpler homogeneous systems. In
the cases when the latter can be solved exactly our method yields an exact
solution for the statistical properties of an inhomogeneous IPS. This approach
is illustrated by studies of three of IPS, namely those with particles of
different sizes, or with varying (between particles) maximal velocities, or
accelerations.
