Most car-following models show a transition from laminar to ``congested''
flow and vice versa. Deterministic models often have a density range where a
disturbance needs a sufficiently large critical amplitude to move the flow from
the laminar into the congested phase. In stochastic models, it may be assumed
that the size of this amplitude gets translated into a waiting time, i.e.\
until fluctuations sufficiently add up to trigger the transition. A recently
introduced model of traffic flow however does not show this behavior: in the
density regime where the jam solution co-exists with the high-flow state, the
intrinsic stochasticity of the model is not sufficient to cause a transition
into the jammed regime, at least not within relevant time scales. In addition,
models can be differentiated by the stability of the outflow interface. We
demonstrate that this additional criterion is not related to the stability of
the flow. The combination of these criteria makes it possible to characterize
commonalities and differences between many existing models for traffic in a new
way
