When I enter a 30 limit and click the ACC to 30 mph from 50 mph, am I correct in thinking that the brake lights activate? I ask because it slows fairly quickly. 

They do indeed light up. It would be a bit dangerous otherwise!

If the Cruise is active at 50mph and you flick the speed down to 30mph then the brakes will apply and brake lights wil go on.

If you are running at 50mph, disengage cruise, set the new limit to 30mph and engage the cruise, then car will coast down and brakes will not apply.

How about when the radar spots a car (i.e. pop up in maxi dot) and 'backs off' by braking slightly, rather than the hard braking from a 20mph (4 taps) speed selection change?

1 hour ago, NJRJ said:

How about when the radar spots a car (i.e. pop up in maxi dot) and 'backs off' by braking slightly, rather than the hard braking from a 20mph (4 taps) speed selection change?

I usually do try to estimate when to tap the brakes, to slow using engine braking for economy and simple good driving. I  used ACC initially to match speed  limits to see how ‘clever’ it is. Being a bigger car, the Superb definitely feels to me that it holds its momentum compared to my Golf/Octavias, when decelerating, i.e. needs a bit more distance - forethought when tapping the brakes, to disengage the ACC, trying to enter the speed limit without further braking, I particularly like the ACC control arm and ease of the 5mph increments in comparison to the steering wheel for CC controls on my Octavias and ACC on the Golf. 

@Redboy You can also increase and decrease the speed in 1mph increments. Pressing the button on the end of the stalk decreases (I think!) And pulling the stalk towards you increases the speed. 

 

I hope I got those the right way round 😂

17 minutes ago, boydeee said:

@Redboy You can also increase and decrease the speed in 1mph increments. Pressing the button on the end of the stalk decreases (I think!) And pulling the stalk towards you increases the speed. 

 

I hope I got those the right way round 😂

You did

19 hours ago, NJRJ said:

How about when the radar spots a car (i.e. pop up in maxi dot) and 'backs off' by braking slightly, rather than the hard braking from a 20mph (4 taps) speed selection change?

The brake lights will go on any time the ACC or emergency braking apply any braking at all.