Stewart and Ford part company.

Ford Motor Company recently celebrated its 40-year relationship with the legendary Grand Prix racer-turned-businessman, Sir Jackie Stewart, which draws to a close at the end of the year.

Stewart and Ford have agreed to conclude their formal association which began in 1964 when the up-and-coming Scottish racing driver was given his first contract to promote Ford products in Britain. Through the next four decades, Stewart influenced Ford people, customers and products globally, carrying through to the latest Ford, Jaguar, Aston Martin, Mazda and Volvo products today.

"I'm 65 years old and it's the right time for me and Ford to start a new chapter with new challenges," said Stewart. "I'm busier now than ever, but serving a global player like Ford the way I have requires an intensive personal time commitment that is becoming more and more difficult to manage among my other commitments. We both believe this is a good time to stop rather than compromise."

Stewart rose to fame by winning three Formula One world championship titles with Ford power in 1969, 1971 and 1973. He then uniquely transformed his career into that of a high-level consultant to Ford and other top companies world-wide.

The relationship between Stewart and Ford became one of the longest of its kind in modern business history, influencing countless Ford Motor Company products and culminating in 1996 with the development of a Ford-powered Formula One team bearing his name, Stewart Grand Prix.

"Jackie Stewart has made a tremendous impact on Ford globally," said Edsel B. Ford II, a member of the board of directors and the great-grandson of Henry Ford, founder of Ford Motor Company. "He has been much more than a consultant because he became so immersed in our business and our product-development processes, bringing his passion for excellence, his eye for detail and his charisma to Ford people and customers around the world. Now, as Jackie's career enters a new chapter, we salute him and thank him for being such a great Ford ambassador."

Stewart built his business career around the same qualities that made him a role model in Formula One.

Renowned for his smooth driving style of powerful Formula One cars, Stewart used his insight to teach Ford employees and customers the fine points of performance driving with an innovative yet easy-to-understand experience called Formula Finesse.

Competing during an era in which injuries and deaths in racing were commonplace, Stewart became a ceaseless advocate for safety improvements that are taken for granted today.

He later campaigned with equal passion for greater seat belt usage and new safety technologies.

Stewart built a reputation for providing his race team with insightful feedback about his racing car's performance on the circuit. Generations of Ford engineers have reportedly benefited from that insight, having learned how to evaluate products on the test track.

Stewart's talent was spotted early by Ford when Walter Hayes, who would later become the godfather of Ford's Formula One programme and Ford's global head of communications, approached the young driver at a motor show in London in 1964. Hayes offered Stewart ?500 to promote Ford products in 1965, along with the white Ford Zodiac that was the centrepiece of Ford's exhibit to drive that year.

"I didn't know who Walter Hayes was, but I did know that to have a contract with Ford Motor Company was a big deal with great opportunities for the future, even though I wasn't yet aware that Ford would enter Formula One," Stewart said.

Stewart cites his work in teaching engineers critical vehicle dynamics evaluation skills as one of his most rewarding activities over the years with Ford.

"Just because you're a good engineer doesn't make you a good driver or vehicle dynamics analyst," he said. "And just because you're a good racing driver doesn't make you a good analyst or communicator. I was fortunate to have the right combination and be able to share my capabilities with many Ford engineers. That certainly will be one of my most lasting contributions."

Stewart was awarded the United Kingdom's Order of the British Empire in 1971 and knighted in 2001.