Spoiler deployment at lower speed?

[RPSN]

Speedos are normally set ~ 4% high. although you'd think the spoiler would be using the same speed signal that the ECU produces.

That extra 4% must have saved some driving licence points

As the speedometer shows a slightly higher than true speed and the rear deployable spoiler operates on the same principal, I'd say they're both using the same speed signal.

[Hammers]

Mine goes up at 103kmh and down when under 80 for a while, not instantly.