The extremely rapid development of the use of scientific computing in car design (75 per year) required the installation of a CRAY XMP supercomputer at PSA. This machine has doubled the group's overall computing power and has multiplied the power of the central plant tenfold. Computation of structure using finite elements with 50 000 degrees of freeedom, which was previously processed on an Amdhal 5860 in 40 minutes, at night, can now be processed in 5 minutes, during the day. This means that the structure can be optimised more efficiently, if there are means available, to modify rapidly the mesh. In addition, models can now be made of new phenomena in the fields of fluid mechanics, combustion, accoustics and the mechanics of non linear structural analysis. By computing the dynamics of gases in the manifolds and taking into account finer hypotheses (threee-dimensional viscous and transcient), flow round the valve and filling of cylinder can be simulated.Complex non-linear behaviour (plasticity, large deformation, contacts) can be taken into account in simulating crash phenomena. The main difficulty in using these methods is the cumbersome meshing stage, to which there is as yet no solution.