This is a very realistic effect that I've managed to program in MMF (construct's still iffy for me, I think my laptop's too pants), and think would be awesome if you could make an effect for it (rather than having to use events).
It would have these parameters:
What it does is thus:
When an object moves very fast, it jumps a few pixels. This effect loops from the start point (previous frame) to the end point (current frame), drawing copies of the object on every step pixels in between.
Additionally, each 'instance' that it pastes has its opacity split this way:
step / distance * 100%
So if the object is moving at 100px/f, that means it's travelled 100px between this frame and the last one.
So instead of drawing just one object, if it has a step of 1px, it'll draw 100 instances of the object, all at 1% opacity.
This emulates very very realistically the motion blur in every day life.
You can see the effect as it appeared in MMF below. It has practically no slowdown over distances of about 300px, even in MMF. So I can't imagine how fast it'd run in Construct!
This last one has got the cleanup routine switched off (since this one is hardcoded in events, obviously), and shows better the effect over several frames.
You know you want that on your Sprites