Just found this site, like alot if not all xf owners my stop start did not work when I had the car which was 4 years old, The show room had it back and put the battery on charge after which it worked for a day! They said the battery was fine.
Having talked to lots of xf owners they all have the same problem, even a new car was ok for 8 months but has not worked since! Was this stop start only put in the car to show good mpg and low emissions? for new sales, if so is this fraudulent a little like diesel emissions cases that have come to light ? My wife has a cheaper older car with stop start and it works fine every time