A maintenance log is only useful if it tells you what’s next. Each row keeps the next-due
date and km the garage gave you; the sheet compares the date with today and the km with the
vehicle’s latest odometer — the highest reading in the log — and flags Overdue or Due soon.
Two triggers, either one counts, and a row with neither stays quiet.
Pro: per vehicle, and on a schedule
Vehicles turns the log around: latest km, cost this year, cost per km from this year’s
distance, and the three dated reminders that don’t come from a garage — tax, insurance,
inspection — with the nearest one named. Schedule is the interval list: oil every 10,000 km
or six months, brakes every 40,000. It finds the last time each item was done for each
vehicle with SUMPRODUCT(MAX(...)) over the log, adds the interval, and reports by date and
by km, whichever bites first. An item never logged says so.
Checked, not just built
The build recalculates both workbooks in LibreOffice and in a second, independent engine and
compares fifty values — days and km to due, each flag, the yearly and per-vehicle costs,
cost per km, the reminders, and every schedule row’s last done, next due and status —
against numbers computed outside Excel.