It seems to me that Girl on a Motorcycle did more than fall short of liberation. From the very title-- using the diminutive instead of "woman"-- it failed.
The strongest parts of the film are wrapped in contradiction. A woman, Rebecca, leaves an unhappy marriage in the stifling complacency of the suburbs to seek sexual freedom, but she finds it in the hands of a rapist. Indeed, her sexuality betrays her all along, becoming an overwhelming obsession with a man who shows her neither love nor respect. The literal vehicle of her sexuality, her motorcycle, is a thing that is traditionally male-- a phallic vehicle that pierces even into her mind, listing her thoughts and imaginings and splattering them across the page.
Her constant sexualization is another, more dominant form of penetration. The writhings of Rebecca's body are as animalistic as the fur she wears. The power of the motorcycle and the intensity of pleasure take her over and own her. Even her daydreams hold men in the position of power, as when the border guards assault her. No statement of her enslavement could be more obvious than the moments just before her death, when she loses herself in her dream and gyrates over the motorcycle, never noticing a second of the pain.
Instead of setting Rebecca free, Girl on a Motorcycle looks into her mind and lingers on her body, and goes to the other extreme of domination.