[janco]

Latency measurement from car side?

[bartkappenburg]

Wouldn't help: the latency to the relay box is at least as good as having the physical key nearby.

[icebraining]

That can't be true, because the request/reply still has to travel all the way to the key and back.

[gambiting]

If the receiver is accurate enough(we're talking nanosecond precision) then you can absolutely tell if the key is 1m or 10m away, so a relay wouldn't help at all.

[GoToRO]

From the video it seems that the car was parked in front of the house and they just amplified the signal coming from the key inside the house. So not exactly a relay attack. The latency increase must be really low.