  We propose and study a nonlocal conservation law modelling traffic flow in
the existence of inter-vehicle communication. It is assumed that the nonlocal
information travels at a finite speed and the model involves a space-time
nonlocal integral of weighted traffic density. The well-posedness of the model
is established under suitable conditions on the model parameters and by a
suitably-defined initial condition. In a special case where the weight kernel
in the nonlocal integral is an exponential function, the nonlocal model can be
reformulated as a $2\times2$ hyperbolic system with relaxation. With the help
of this relaxation representation, we show that the Lighthill-Whitham-Richards
model is recovered in the equilibrium approximation limit.
