  This paper is concerned with the construction of a fast algorithm for
computing the maximum speed of propagation in the Riemann solution for the
Euler system of gas dynamics with the co-volume equation of state. The novelty
in the algorithm is that it stops when a guaranteed upper bound for the maximum
speed is reached with a prescribed accuracy. The convergence rate of the
algorithm is cubic and the bound is guaranteed for gasses with the co-volume
equation of state and the heat capacity ratio $\gamma$ in the range $(1,5/3]$
