enum model_class
{
    ...
};

struct SModelData
{
    string       m_strName;
    model_class  m_class;
    vector<int>  m_parts;
    int          m_iSeats;

    SModelData(...) : ... {}
};

const multimap<int, SModelData*> models_data =
{
    { 400, new SModelData("Landstalker", STUFF, ***, 4) },
    ...
};