The craft of auto trim is usually learned through a vocational training program, long-term apprenticeship or a combination of both. It's rare, however, that either track teaches those elements of industrial design - like illustration and 3D modeling - that automakers use to build modern interiors.
Of course, having a background in industrial design isn't necessary to be successful in the field. Some of the best and most-innovative custom trim shops never touch a computer. But if it's something that you're interested in pursuing, Coventry University is the place to enroll.
Check out this cool video showing the types of skills taught at Coventry: http://tinyurl.com/c9jas6s