In his spare time, he started submitting drawings to auto magazines and soon became a regular contributor to "Motor" in Sweden.
He remained loyal to Saab ever since, moving to wherever the passenger car business had its headquarters: first to Södertälje and finally to its present location in Nyköping, just 60 miles south of Stockholm.
At Saab, Sjögren became deeply involved both in the shaping of the advertising material used to sell the cars as well as in the design and color scheme advisory groups.
He was a nature lover who made it a habit to learn the Latin names of plants and flora and fauna that came his way - all of which he could depict in characteristic line drawings with great accuracy.
Other indoor interests that served as a background to his major pursuit were classical music, with a strong penchant towards the Vienna school, smoking a pipe or a cigar and enjoying a glass of good wine or Scotch whisky.