He also worked on the design and development of heavy-duty truck transmissions in the engineering and experimental departments of the Fuller Manufacturing, a subsidiary of the Eaton Corporation.
As a public-affairs official with General Motors Overseas Operations in the 1960s, Ludvigsen was responsible for all the company's product information outside the USA.
This encompassed the design, engineering, tooling, production, marketing, distribution and sale throughout Europe of special automobiles, light trucks and parts.
He was in charge of the design and launching of the RS1600i Escort, which was named Motor Sports Car of the Year in France and which led Ford's RS Products operation to record profitability.
His books on the latter subject have won the Montagu Trophy (once) and the Nicholas-Joseph Cugnot Award (twice),[note 1] both recognizing outstanding automotive historical writing.
In 2001 he again received the Cugnot award from the Society of Automotive Historians (SAH) for his book about the early years of the Volkswagen, Battle for the Beetle.
He followed this with Jackie Stewart: Triple-Crowned King of Speed and Juan Manuel Fangio: Motor Racing's Grand Master.
Fourth in this series for Haynes Publishing was Dan Gurney: The Ultimate Racer and fifth was Alberto Ascari: Ferrari's First Double Champion.
His introduction to At Speed, a book of Jesse Alexander's racing photography, won the Ken W. Purdy Award for Excellence in Automotive Journalism.
In 1996, publishers in Britain and the United States launched Karl Ludvigsen's book on motor-industry management, Creating the Customer-Driven Car Company.
It advises industry personnel on customer-pleasing best practice researched during 15 years of in charge of a London-based motor-industry management consultancy, which he founded in 1983.
Ludvigsen and his team worked for most of the world's leading motor manufacturers in strategic planning, brand reinforcement, distribution, company structure and organization, mergers and acquisitions, and on design and engineering issues.
From 1980 through 1984, Ludvigsen was a member of the Policy Forum of the MIT Future of the Automobile Programme, the most comprehensive trilateral study of the motor industry ever undertaken.