I also keep a ring binder for each vehicle. Every invoice, work sheet or MOT etc. are recorded and stored. The physical maintenance record pays dividends regarding selling price when the time comes…..I keep a maintenance ring binder with sheets for each bike, Madness has five pages filled and a lot hasn't been recorded.
The cars each get a little notebook in the glovebox.
I've never opened an MC brake system that didn't need clean up.