What is the advantage of adaptive cruise control over the standard one that comes with the vehicle? Also what does it take to retro fit it?

Some love ACC others don`t - I personally think its a god send on the motorway contraflows - as for retrofitting - I think its a no no - there`s the radar on the bumper - dash switch & steering wheel controls that will be needed  16MY Estoril Blue SVR.............
17MY Autobiography Dynamic - Corris Grey - WOW.
14MY Autobiography Dynamic - SDV6 - Fuji White
12MY Autobiography - SDV6 - Santorini Black - Dual View - Rear Entertainment - Sunroof.
12MY Autobiography - SDV6 - Orkney Grey - awesome ;(
2005 Java Black - 4.2 V8 Supercharged First Edition- will never be forgotten ;(

The cost of the front radar alone will make the cost of retro-fitting prohibitive.

Phone your local dealer for a price. Make sure you are sitting down

Aside from the price of the parts it is likely to be a very involved retrofit but the setup as standard is fab. On the TDV8 the cruise is superb, very fluid when the road clears in front of you again, unlike my wife's Galaxy where adaptive cruise works very well but it has to think for about 2 seconds when the road clears and you are waiting for it to pick up again.

Got it on mine , love it !

The only reason I have asked is that we are having to replace the front bumper due an incident with small deer and the replacement bumper skin has the moulding for the adaptive cruise control. But from what I am reading here the radar cost will make the bumper seem cheap.

To retro fit it is easy I fitted the kit on my D3 but could not get it to work fully, it was done as a test to see what was involved and has DM has pointed out some of the parts prices will make your eye's water.

Flack

The radar alone, is over £1900 + VAT

 2014 L405 SDV8 RR Autobiography

2012 RRS SDV6 HSE -Orkney Grey with A/B bodykit - Now Gone
2007 RRS TDV6 HSE - Zermatt Silver - Gone

As it cost me a fiver for 4 plastic trim clips (to hold the heat shield in the front wheel arch) I can believe a bit of clever tech would cost c.£2k. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed