Companies get patents for all sorts of trivial ideas, so just in case I decided to gotta go fast and make this idea public without having anything to show.
The idea is that with texture-motion blur the polygons themselves don't blur, but instead the textures. This probably looks less weird in a racer than a first-person shooter, because there is less variety in the direction of movement. Think of the red-white-red-white stripe textures that you often see at the boundary of a racing track. This texture could change to a more blurry one based on your speed. This could either be done by applying a 2D motion blur algo to the texture in real time or by changing between different pre-baked textures. I'm thinking doing the latter just based on movement in one direction.
The pre-baked version sound like taking a lot of RAM, but if it is only applied to a couple textures, like the asphalt and boundary of the racing track, it wouldn't take much. Doing this only partially might look too weird. If the racing track itself is small, it could be applied to all its textures. (The skybox could also have a 2D sideways motion blur for fast turning. Again, this could be real time or changing between different pre-baked blur-levels.)
Remember that the geometry itself wouldn't blur. Would that look too weird? Is the idea maybe more suited for a racer with a cel-shaded look?