  High temperature gases, for instance in hypersonic reentry flows, show
complex phenomena like excitation of rotational and vibrational energy modes,
and even chemical reactions. For flows in the continuous regime, simulation
codes use analytic or tabulated constitutive laws for pressure and temperature.
In this paper, we propose a BGK model which is consistent with any arbitrary
constitutive laws, and which is designed to make high temperature gas flow
simulations in the rarefied regime. A Chapman-Enskog analysis gives the
corresponding transport coefficients. Our approach is illustrated by a
numerical comparison with a compressible Navier-Stokes solver with rotational
and vibrational non equilibrium. The BGK approach gives a deterministic solver
with a computational cost which is close to that of a simple monoatomic gas.
