You can probably guess without using PII. In the UK numberplate info is public, you can look up the make, model year and colour of a car just using it's numberp

You can probably guess without using PII. In the UK numberplate info is public, you can look up the make, model year and colour of a car just using it's numberplate, and anyone can do this. Using that info it would be trivial to detect a BMW car that was older than X years old. Where X is number of years the normal non-extended warranty is. You then just assume that any car older than the non-extended warranty doesn't have an extended warranty and display the advert. Then the only thing the advert would be giving away is that there is a BMW nearby that older than X years. Which anyone with a pair of eyes could figure out because the numbers of UK numberplates encode the issue year (thus the age of the car), and well, BMW's are pretty easy to identify just by looking at them.