- Party A takes the council 4 years ago
- Party A implements the low emissions zone
- Party B goes into elections campaign championing a reverse of the LEZ. The quote about they saying pollution and jams are part of the city's identity is true.
- Party B does not win the election but, because of how the system works, they could take the council by joining forces with other parties (who were also against the LEZ)
- If last point indeed happens, then they will revert the LZE
Actually, it is very possible that the LZE cannot be reverted because of EU's restrictions and fines for pollution quotas. Some media that are sided to Party B and were very critical of Party A and the LZE are now changing headlines to blame EU for the LZE, in what looks like a damage control operation now that they realise the possibility of their promise being not able to be fulfilled.
Source: I live somewhere some consider is Spain and some not.