  Based on the Dirac equation, the behavior of relativistic electrons which
tunnel a potential barrier of height V0 for incoming energies between V0 and
V0+m is studied by using the wave packet formalism. The choice of this incoming
energy zone guarantees that only electrons participate to the tunneling
process. In the opaque limit, as shown in a previous analysis, the transit
velocity is proportional to the barrier width and for relativistic potential
tends to a constant value greater than $c$. In this paper, a new numerical
study shows a very surprising result: superluminal transmissions are also
evident for thin barriers.
