I'd like to query the forum on how all you gearheads may collect data. Personally,  I like to create spreadsheets in which I wll create different car modules (for example, tires,  or brakes,  etc)  to cover every aspect of my truck.  And for each module, I collect and record a range of parameters that I can monitor over time to track behavior.  For example..for tires, I would collect air pressure, tread depth,  wear pattern.  For brakes, i would collect disk thickness,  pad thickness. For engine, maybe cylinder compression, engine idle rpm,  idle MAF etc.  I do this in addition to my more descriptive general  mnt/repair  log.  I would be interested in compiling a full list of things to track across all modules and wanted to get suggestions from anyone.