This paper outlines an approach to model some of the effects of strain-rate in the simulation of thermoplastics in high speed crash simulations. The effect of strain-rate on the material properties can be significant for thermoplastic materials. The models currently available in simulation software were designed to fit more traditional materials, with a limited sensitivity to strain-rate. In order to more accurately simulate these effects, routines are being developed to extend the material models to more accurately account for material properties such as modulus, yield and failure strain variations with strain-rate.These improvements in simulation capabilities lead to more accurate predictions of mechanical behaviour of thermoplastic materials in crash situations. Such improvements enable more optimisation of system designs leading to weight reductions, shorter development times and hence lower costs.