  The Poisson point process (PPP) is not always a realistic model for the
locations of vehicles along a road, because it does not account for the safety
distance a driver maintains from the vehicle ahead. In this paper, we model the
inter-vehicle distance equal to the sum of a constant hardcore distance and a
random distance following the exponential distribution. Unfortunately, the
probability generating functional of this point process is unknown. To
approximate the Laplace transform of interference at the origin, we devise
simple approximations for the variance and skewness of interference, and we
select suitable probability functions to model the interference distribution.
When the coefficient-of-variation and the skewness of interference distribution
are high, the PPP (of equal intensity) approximation of the outage probability
becomes loose in the upper tail. Relevant scenarios are associated with urban
microcells and highway macrocells with a low density of vehicles. The
predictions of PPP deteriorate with a multi-antenna maximum ratio combining
receiver and temporal indicators related to the performance of retransmission
schemes. Our approximations generate good predictions in all considered cases.
