We know about tuner divisions, like BMW's M division or Mercedes-Benz's AMG division or Fiat's Abarth division. But where did they first start?
I haven't the faintest idea.
I do know, however, that AMG and Abarth started out as independent tuning companies and were eventually bought out by the companies they specialized in. Not so the M-Division, which began as the Motorsport Division, making racing parts for BMWs. The first car made by the Motorsport Division was the 3.0CSL of the early 1970s.
Some may point to Scuderia Ferrari as a tuner division of Alfa Romeo, but they point in vain. Alfa Romeo made the cars, Scuderia Ferrari only raced them. They were basically Alfa Romeo's unofficial racing team.
The earliest in-house tuner division I know of, though, is within a rather surprising company: Morris, in England. Morris is known for making low-end cars like the Minor or the Eight.or the Oxford. Morris general mangager Cecil Kimber came across the idea of making sporting and/or race-ready Morrises. Their first car was a sporting version of the Morris Oxford called the 14/28. The enterprise was called "Morris Garages", eventually MG for short.