Bosch Siemens AG operates in 60 countries and its subsidiaries make up 60% of turnover. The group was operating outside what has become the EU long before it existed.
VW took over Seat (Spain) and Skoda (Czechoslovakia) long before those countries even applied to join the EEC/EU.
Fiat was making cars in Russia, Yugoslavia and Poland long before the enlargement of the EEC began.
Being a member, or not being a member, of the Common Market/EEC/EU has been no impediment to moving production to cheaper areas. It has been a tactic long employed by big businesses since time began. National governments have to work to EU rules but they cannot prevent private companies from making business decisions to benefit the business.
One other thing about the EU and free movement. The free movement is of labour not the free movement of populations. Anybody is free to move around to look for work, but countries in which they are seeking work can impose restrictions whilst they are looking for work. In some countries of the EU those restrictions are forcefully applied.