Speaking purely in terms of the PC version, there is no ghosting to be observed whatsoever, at least in my build (latest version as of this post, whatever that is). It's running at pure 60FPS, and there are no blends to be seen anywhere. The only motion blur of any kind that is visible in the footage and static screenshots is the real, smearing motion blur that is properly implemented and excludes cars.
From the screenshots you can see that it's working properly, the background is heavily blurred from the movement but the R8 is clear (besides video compression artifacting of course, but that looks very distinct from ghosting).
The PS4 footage on the other hand has two possibilities that explain the ghosting:
1. All footage captured so far by everyone is resampled, giving the ghosting effect. This is seeming less likely as the Digital Foundry screenshot above looks like a direct framegrab from the game as opposed to a frame from a video. It's possible that their capture equipment introduces the ghosting, but it isn't present in the XB1 equivalent.
2. The PS4 has an issue with rendering in the game where it, and only this version, suffers from ghosting. This is the one that looks more likely now from the proof posted above. Since the Xbox One and PS4 comparison in hesido's screenshot is from Digital Foundry, we can assume they were captured in the same environment, yet the Xbox One version has no ghosting.
The ghosting seems to affect everything on screen, including regions smeared by motion blur, but it's most noticable on aspects that don't receive any blur, such as opponent cars and HUD elements. Most visible when something is moving fast, as there has to be a big difference across two frames to see it. If it turns out that there is ghosting in the PS4 version, then the PS4 version is the exception/outlier as the PC and XB1 versions don't suffer from any whatsoever. PC I can vouch for personally, XB1 version I can only speak in terms of video footage I've seen from others.
Hopefully that covers what you're asking for.