Having done a ton of driving for many years with my husband's kids, I sympathize with how frustrating it is to be in the car all the time.
Unfortunately, you agreed to a provision that's now in your divorce decree. And then, knowing about that, you moved 30 miles away. I don't see any way that it's not your problem to deal with.
If I understand this, you and your ex both work (and he pays the childcare and the medical coverage), and his wife provides daily care of your children after school (which saves you money). You have another son (not his, right?) who has daycare in an inconvenient location, and you want that to be your ex's problem. I think it would be great if, now and then, he helped you out of a bind by driving them, but I don't see that it's the battle you really want to fight.
If he moves farther away for any reason, you say you would still have to drive. I don't think so. You could file for a modification of the order - which I think you could do at any time - and either work it out with a mediator or let a judge decide. I don't know all the towns you list in your post (nor do any of us across the country), but sure, if he moved to the other end of the state, you'd have a good argument and you'd probably have to revisit the entire custody arrangement. Only you can decide if this is a serious enough situation to be worth the legal fees (lawyer, mediator, court costs) to file now. But you might be a lot better off just sticking to your agreement, which makes it harder on you (the one who decided to move) and hope that being cooperative leads him to compromise on something else down the line.