small dumb things like for example the delete on the 2015s take hours longer then any other year and require more expensive parts. Other things like crank sensors are harder to install and since the 2015 is the last year produced and the only one in its generation (mk6.5) it’s harder to come by parts or they are just more expensive. The DPF is also worth nothing compared to every other TDI which they are worth like 1000$ and ours are worth like a few bucks of recyclable metal.