A scene: A woman with a extra long scarf around her neck driving a red drophead car and when shes on the road her scarf gets caught in a wheel and kills her. this might be the opening scene of the movie.
“Isadora” (1968), with Vanessa Redgrave in the titular role?
The movie ends as you described. Quote from the below Wikipedia page of the movie:
“She goes for a drive with him in his sports car, and as they roar along a road by the sea, Isadora’s long chiffon scarf catches in the spokes of a wheel and strangles her.”
And the biography of Isadora Duncan on her own Wikipedia page also mentions how she died. Quote from her biography on her below Wikipedia page:
“She died when her scarf became entangled in the wheel and axle of the car in which she was travelling in Nice, France.”
Just for your information, there is also a lesser known BBC TV movie about her life, but you probably saw the much more well-known 1968 movie “Isadora” above with Vanessa Redgrave.
Here is the link for the lesser-known BBC TV movie (again, as I said, you probably watched the other movie above with Vanessa Redgrave, the 1968 version):