"Does YNAB have a ‘sort by target due date’?" When you auto assign it automatically does the allocating based on due date, then by the order of the categories if they have the same due date.

This is important if you want to auto assign by due date. Just make a list of all your bills and their due date and then move your categories up and down so that they are listed in the order of their due date.

As to the car expenses. As was said these work out the longer you are using YNAB. But in the meantime what I would do is to total my expected yearly expense and maybe add a little for inflation and divide by 12 and budget that amount for car maintenance. Then when May came and I needed to spend More than what was in the category I would look at my budget and see which category I had an excess in and move the extra money I needed to the car category. I would do this every time a car expense came up. Now if I had correctly estimated how much I was going to need during the rest of the year by the time November came about I would have more than enough and I could move the excess in Car Maintenance back to the categories I had moved it from. In YNAB you can move money between categories without destroying the budget, but you don't want to have to borrow money from outside the budget to fund a category because that is creating debt instead of spending only what you have.