Using the extended Nagel–Schreckenberg (NS) model, we numerically study the impact of the heterogeneity of traffic with speed limit zone (SLZ) on the probability of occurrence of car accidents [Formula: see text]. SLZ in the heterogeneous traffic has an important effect, typically in the mixture velocities case. In the deterministic case, SLZ leads to the appearance of car accidents even in the low densities, in this region [Formula: see text] increases with increasing of fraction of fast vehicles [Formula: see text]. In the nondeterministic case, SLZ decreases the effect of braking probability [Formula: see text] in the low densities. Furthermore, the impact of multi-SLZ on the probability [Formula: see text] is also studied. In contrast with the homogeneous case [X. Li, H. Kuang, Y. Fan and G. Zhang, Int. J. Mod. Phys. C 25 (2014) 1450036], it is found that in the low densities the probability [Formula: see text] without SLZ [Formula: see text] is low than [Formula: see text] with multi-SLZ [Formula: see text]. However, the existence of multi-SLZ in the road decreases the risk of collision in the congestion phase.