So does anyone track this stuff? Does anyone manage to a budget?
I have a monthly flight budget, yes. Whether or not I stick to it every month is another matter entirely.
Excess (if I don't fly) even sits in a separate account at my bank. If I'm short, that's a pre-discussed item with the Mrs., who is awesome and usually doesn't mind.
Of course, it helps if the reason I went over was to take her someplace fun in the airplane.
The Instrument rating was a temporary increase in the monthly budget until the flying account hit a dollar amount we both figured would conservatively work to get it done. That took about eight months to build up and we discussed that it was a "go until finished" kind of project, so it could go out of bounds a bit. Kinda like some of the house projects over the years.
As far as the airplane goes, yes, we could also pull the percentage of costs that fuel represents. Having a co-ownership means tracking stuff so there no surprises.
One of my (totally awesome) co-owners has the master spreadsheet and sends the other two of us a copy with our monthly bill. Since one person sends the checks to the hangar and another sends the aircraft check, and someone usually runs the annual on a miles or points credit card, the LLC has to track those as credits, versus those of us who haven't paid for various things that need reimbursement, so there's a page of credits/debits. We review and whoever is under, writes a check to the LLC, and the other person has a carried credit they usually fly off that month. (In my case, I bank transfer to the LLC because I hate dealing with checks.)
So yeah... We have all the numbers.
Now, whether we want to delve into things like the fuel percentage, is another matter.
If we do, it's easy to add a column to calculate it.
We're usually more interested in what the percentage that maintenance and improvements run than what fuel costs. Fuel is what it is.
We also did track a few purchases of MoGas separately since we had a tank, and that was an outflow for the person who fueled that tank and shuttled it to the airport.
We may do more of that since one co-owner built a tank trailer.
The LLC also has to provide appropriate tax forms annually. Our person who's doing the spreadsheet kindly sends us those also.