This sounds silly and I am embarrassed but many times I remember saying I will never drive a minivan. Besides the fact I am scared because they are huge/bulky, I consider them so typical of the hemish world and I never wanted to be that type of family driving around with a bunch of kids in a van.
Now BH, 4 kids later and we just purchased a minivan which I obviously now have to drive. I never actually promised or vowed I wouldn’t drive one but I feel bad for saying I won’t drive one. Do I have to do hataras nedarim to actually drive it? Sometimes I added in bli neder but don’t know if I did every time.
You can be matir the neder. You are allowed to be matir this because you never realized that what you would eventually be very practical for you, and difficult to manage without. It is not considered a neder l’dvar mitzva, because your reasons for not wanting to drive the van were not mitzva related.