Well, if it works like the diesel ones, it _should_ burn itself clean periodically. Problems arise if you do a lot of short commutes / city driving when the engine doesn't start the burn process at all (takes about 20-30 mins) and the filters eventually get clogged and need to be replaced -> diesel filters cost anything between 1-3k€ plus labor. I've talked to various diesel drivers around here and earliest replacements start around 50-60k kms.