Good agreement between a hydrodynamic and a Monte-Carlo device model is demonstrated in this paper for an advanced SiGe Heterojunction Bipolar Transistor. This result is based on two principles: 1) Extraction (from the Monte-Carlo bulk model under homogeneous conditions) of the relaxation times τ at discrete points of the parameter space spanned by the Ge-content x, doping density N, carrier temperature TC and lattice temperature TL.2) Modeling of the relaxation times τ(x,TC,TL) by splines.