Interested in Language
I work for a large European car maker. I work on car design.
I wonder if 'in' would be OK too.
zi think it would be all right. I doubt anyone would pay any particular attention to the expression "IN car design."
I think it has a slight implication that you work in the Car Design Department, or in the field of car design. It recalls the expression, "I'm in sales."
"I work ON car design" sounds more like you have a lab bench where you go to make design models, or a CAD thing or something. It recalls the expression "I'm working on it." For whatever reason, it gives off the faint implication that you don't design cars only, but work on this task on and off.