[GMcL]

Maybe the exceptional tyre wear is also down to the car originally being homologated with higher spec tyres (weight rating) to accommodate the extra weight of the original 5 & 6 cylinder cars.

If the original specification was at the lower end of the weight rating for the 6 cylinder then a drop in weight rating would be possible with the lighter 4 cylinder cars. Of course only the tyres listed in the vehicle documentation can be used but it could simply be down to over specified tyres from the outset combined with the reduction in vehicle weight by downsizing engine capacity.

If anyone is really interested take a look at the new XC60 data and see what the tyre specification (weight rating) and vehicle weight is and compare like for like vehicle e.g. D4 R-design old and new.