That would be like Construct's built in blur, a kind of effect which is not even done for feature films . They use postprocessing with velocity buffers, which in 2D yield the same speed for a whole sprite UNLESS ITS ROTATING.
So... this should be good enough except for the rotation case, which I'm thinking about but can't quite come up with a nice effect for it
It's hard to notice the details in fast moving objects so don't worry about velocity changes between frames. Physically accurate blur shouldn't be larger than the distance travelled by the sprite in screen space, so you couldn't tell the difference anyway.
Oh yeah and I overdid the blur size
hit the bounding box, didn't notice that. Size is bounded by Construct.