Interesting if a bit old thread!
I saw some posts about Grimsby and Southampton and I thought I would like to share some of my knowledge with you.
About 15 years ago I used to work at Grimsby employed by Toyota. I also spent time in Southampton also working for Toyota.
My role was within Logistics responsible for the import and export of new vehicles.
Grimsby is the export centre for all Derby produced Toyota (was Avensis and Corolla not sure now as I don’t work there anymore). It was also the import centre for Audi, VW, Seat and Skoda). French produced Toyota Yaris were also imported to Grimsby. BMW also imported. Probably all changed now.
Grimsby has access restrictions so in terms of car ships they were short sea types with approx 1000 car capacity.
Southampton different set up. Deep sea vessels with 8000 car capacity and major import export hub. Jaguar Ford used to be Honda and mini all exported Southampton.
There are other large operations at Newcastle Portbury nr Bristol, Sheerness in Kent.
Cars just like containers are imported and exported on the same vessel hence lots of rh/lh cars next to the sea.
UK is 3rd biggest car market in Europe hence the large volumes of cars you see. When I worked in Grimsby we received 50 lorry loads from the factory every day just for export.