  In this paper we test a special-relativistic formulation of Smoothed Particle
Hydrodynamics (SPH) that has been derived from the Lagrangian of an ideal
fluid. Apart from its symmetry in the particle indices, the new formulation
differs from earlier approaches in its artificial viscosity and in the use of
special-relativistic ``grad-h-terms''. In this paper we benchmark the scheme in
a number of demanding test problems. Maybe not too surprising for such a
Lagrangian scheme, it performs close to perfectly in pure advection tests. What
is more, the method produces accurate results even in highly relativistic shock
problems.
