It is the cost you have to pay each week for each vehicle you own.

My question is, does it change itself according to what you set passenger capacity, speed etc. ? So far it hasn't seemed to go up at all, is it meant to go up automatically? There doesn't seem to be anything stopping me from decreasing or increasing it which is strange. What effect would it have if I increased or decreased it? When I increase passenger capacity, the maintenance doesn't go up lol?

By default all vehicles cost 800 (8.00₡) each week. If no maintenance cost is set IPT will calculate a value based on capacity after that it is up to you what value you use.

Maybe I'll make some changes in a future update so that the cost is always bound to capacity.

Thanks for the reply. How do I set 'no maintenance' so that I can manually let it calculate? It always defaults to 8.00₡ when I take the number away and leave nothing there.

On the note of adding it automatically for a future update, I would second that very much. It would make a lot of sense :)

Thanks for the replies. Chris, by having no maintenance cost set I think he's referring to custom vehicles, at least that's how it works for me. Standard buses are indeed 8.00₡ as default, however I have several custom buses that I use and due to the fact that the developers of those must have left the maintenance area blank when they developed them, these custom buses default to much higher values in maintenance. For example I have a 115 capacity coach that defaults to over ₡30 in maintenance costs.

I'm not sure how to make the mod change the maintenance cost of normal buses to work based on capacity manually, I'm as clueless as you on that, but I'm also not sure if it's actually doable. It might be up to you to independently increase the cost if you want things to be harder and more realistic.

Oh I see, that would explain it. I've only been using normal vanilla assets so i'll need to get some of those. I do like the idea of it being realistic . Thanks :)

Sorry for late reply.
1 (0.01) is the lowest possible value.
The maintenance cost will change when you submit a new capacity value with the next update but you will still able to override that with your own values.

Does the budget slider do anything for public transport if not using the budget-controls-vehicle-numbers in this mod?

Yes the slider will change the maintenance cost for all public transport buildings and it also increases/decreases the incoming trains from outside connection according to the ingame tooltip.