Your comments

I don't know how the database looks like.
But somewhere in there, there are "odo" inputs.
I'm thinking one is for sure in "Fuel", the other one in "Reminders".
The "Track" should check last "Fuel odo" and last "Reminder odo" and see which is newest.
Than it should just display difference between "Track odo" and the latest "odo" there is.
The other way to do it, is to modify writing process so the "Fuel" input was writing "odo" in two places.
One for "Fuel", one for "Track".
I would help, but I am more Computer Graphic and Webmaster than a good programmer. However I like problems, so if you need to talk some things through with someone, I'm in :)
Not exactly,
Reminder - as name goes, is being set for reminding of something. It works on time and km.
Should be set:
- km from now
- when odo reached
- at exact date
- days from now
- and maybe it could be recurrent, but you would have to assume that we all sometimes do something far from the exact it would have to be not every 400km...but since we set it, reminder should occur after 400km and there should be a reset button when we do it, and counting should start since button was pressed/new odo was added, not after 800km from the first set point.

Cost - is to add additional costs.
This is something most of us don't really care. But don't get me wrong...fuel costs are separate thing, I'm talking about additional costs. You should separate Reminder and Cost, or allow us to create template where we can choose what fields we want and what not, and what should be count between two occurrences of the same thing. Because sure, I'd like to add repair costs when my car goes to mechanic, or when I change tires for winter as an additional cost so it was added to the whole car cost every month/year, but not every time, everything. Sometimes it doesn't matter. Sometimes I want to track just km from the "add point".

If you separate Costs from Reminder, sure, than Costs can target adding costs in any way, but than in other places (like Reminder) should be as an option. If you want to keep it together, this should be "optional" in "add points" at the bottom, not a target.

Why I think Reminder is wrong?
Because it is all together now, and there is no understandable goal in it. Everything was put in one place and named Cost/Reminder and it is a mess. At least for me. But idea is good. I really do appreciate the all work.

And me, I just want to know how many km I am going since I did something last time, not looking for reminder to tell me that I have to do it now.
When I add Reminder/Cost in Fuelio, because I do, I really use that option so I remember when I did something, unfortunately in Cost log I see category, date, name and odo - and Fuelio is not calculating distance between two occurrecnes of the same thing. I have to take calculator and do it myself. And I'd like Fuelio to do it for me.
I'd like to know how many km my brakes lasted untill change...this would help me know, and "know" is what I want.
I'd like to know how many km I made since oil, now, how many it is now, and I can't see it. I have to count with calculator. I'd like to have this number on main screen, next to information that I am riding on Motul 7100 oil. That my chain did so far lasted xxxkm since I replaced old one. And when I add new occurence the counters reset.
It would be so great to have that. It would be like car computer.

You can name this "Track" option that we can add. And when we add one, maybe a checkbox to show it on main screen.
However in "Cost log", or "Track log" it should be like in "Fuel log": +192km since last add point. This is what I am looking for. And probably lots of people that write feedbacks saying that they would like to have option to add breaks and oil info wish for something like that, not that what it is now in "Cost/Reminder", cause we all know that it is there, it just dont't do what we all want.
I agree, the Reminders are a mess. Very not user friendly. They do not do what users expect it to do, or...Fuelio has no option that users still look for.

e.g.: I have a motorcycle, I would like to track information when I lubricated my chain and how many km were between lubrications, so I'd like to have "add" option that has input fields: "name", "date", "odo counter" and "note" (no price, no nothing else). I'd like to add quick info when I lubricated my chain and have history displayed just like fuel have.
That it showed me how many km I made from the last lubrication and have history of it.
The same goes as to brakes...we don't need info about costs or a reminder. What we are looking for is the history when we did it and how many km we've made from the time we have put new ones (and the "note" field is to write what kind of brakes we have bought - company, model number).

The same goes for lots of other things, like engine oil change, we don't need price, just "name" - that it is oil change, "date", "odo" and "note" - so we can write what kind of oil we have put in. The rest what we need is showing how many km we have made since than. And when we change oil again, to have a history of every oil change just like we have on fuel fill ups.

Fuelio could have joined info. Every fuel fill up, it could show how many km We have made on this oil, and how many km my breaks did since I've put new ones, and how many km I have made since I lubricated my chain, and how many days left of driving with valid insurance and technical examination of the car.

Those are options in Fuelio we still look for. It should be seen on main screen or every fuel fill up because it is something we are doing most common.

Current Reminder option, even though is customizable, is very unhandy and cost orientated, what we do not like.

Please do what we need to have.
This way, we would have all maintance history of our car in this app.

Lately I had to change bearings in my wheel, that would be something I'd like to add to history of my car. But not as cost or reminder. Just add as history of this car, and what I would like to have to remember is "date" when I did it, and "odo", and "note" what kind of part I bought (company/model).

So maybe a customizable "add" option should be with option to track "km" or "date from" or "date to" since the last time of appearence of this particular data input.

Thank you.