Carvico⬇ Fuel log template CSV · opens in Excel, Sheets, Numbers ⬇ Service log template CSV · oil changes, repairs, DIY
Both files come with five example rows so the format is obvious. Delete them and start typing, or keep them while you get the hang of the partial fill-up rule.
Why two sheets, not one
The single most common mistake in homemade car logs is one giant sheet with a "type" column and thirty fields, most of them blank on any given row. Fuel entries and service entries answer different questions and want different columns. Keep them separate — two sheets in one workbook, or two files.
- Fuel log answers: what is my real MPG, what am I spending per mile, is economy trending down?
- Service log answers: when was this last done, what is due, what has this car cost me to maintain?
The columns, and why each is there
Fuel log
| Column | Example | Why |
|---|---|---|
| Date | 2026-03-14 | Use ISO format (YYYY-MM-DD) and every tool on earth will parse it without an argument about day-vs-month order. |
| Odometer (mi) | 42533 | Absolute reading, not a trip meter. Survives forgotten resets and battery disconnects. |
| Volume (gal) | 11.4 | Straight off the pump. Put the unit in the header, never in the cell. |
| Total Cost | 38.76 | Total, not price per gallon — you can always derive the unit price, but not the reverse if you rounded. |
| Full Tank | Yes / No | The column that makes MPG honest. See below. |
| Station | Costco Sunnyvale | Useful more often than you would think — for warranty questions and for noticing which station your bad tanks came from. |
| Notes | Road trip week | Context for the outlier you will stare at in two years. |
Service log
| Column | Example | Why |
|---|---|---|
| Date | 2026-06-11 | The calendar half of every maintenance interval. |
| Odometer (mi) | 46002 | The mileage half. Both are needed — a good interval is "whichever comes first". |
| Service | Transmission fluid service | Specific beats vague. "Front pads and rotors", not "brakes". |
| Cost | 289.00 | Parts plus labour. Zero is a valid entry for warranty or recall work. |
| Where | Main St Auto | Shop name, or "Home" for DIY. This is what makes the record credible to a buyer. |
| DIY | Yes / No | Lets you separate labour saved from money spent when you total the year. |
| Notes | Next due 106000 miles | Where part numbers, fluid specs and the next-due mileage live. |
The formulas
Assuming the fuel template's layout — date in A, odometer in B, volume in C, total cost in D, full-tank flag in E — with data starting on row 2:
MPG =(B3-B2)/C3
Price per gallon =D3/C3
Cost per mile =D3/(B3-B2)
Note which row each number comes from: the miles span two rows, while the gallons and the cost come from the later row. The fuel you just bought is the fuel you just burned. That is the full-tank method, explained properly in the MPG guide.
The partial fill-up rule
If the tank was not filled completely, that row has no valid MPG — you do not know how much fuel is in the tank, so there is no bookend. Do not divide anyway, and do not delete the row (the gallons are real money and the miles are real miles). Carry it forward: add the partial's gallons and miles to the next full tank and compute one figure across both.
A formula that does this automatically for the common case of a single partial:
=IF(E3="No","",(B3-INDEX($B$2:B2,MATCH("Yes",$E$2:E2,1)))/SUM(INDEX($C$2:C3,MATCH("Yes",$E$2:E2,1)+1):C3))
It is doable, and it is also the exact moment most people discover why fuel-log apps exist.
Service-side totals
Last time this was done =MAXIFS(B:B, C:C, "*oil*")
Miles since =current odometer − the result above
Two summaries worth building
Once there is a year of data, two small tables do most of the work:
- Rolling MPG. A 5-tank rolling average alongside the per-tank figure. Single tanks are noisy; the rolling line is where a genuine change in fuel economy becomes visible. If it steps down and stays down, work through the fuel-economy drop checklist.
- Cost per mile by year. Fuel plus service, divided by miles driven, one row per year. This is the number that answers repair-or-replace — the full method is in the cost-per-mile guide.
Where spreadsheet logs actually fail
Not on capability. A spreadsheet can compute anything an app can. They fail in four specific, predictable ways:
| Failure | What it looks like |
|---|---|
| Entry friction | You are at a pump, in the rain, with a phone. Typing seven cells into a spreadsheet app on a 6-inch screen is not going to happen every time — so receipts pile up on the passenger seat and the log falls three weeks behind, then permanently. |
| No reminders | A spreadsheet cannot tell you the oil is due in 400 miles. It answers questions; it never asks one. Every deferred service in your life is downstream of this. |
| One-copy risk | The laptop dies, or the file lives in a folder called Documents/old mac/desktop/stuff. Cloud sync solves this and most homemade logs still do not use it. |
| Formula rot | Insert a row in the middle and the relative references quietly stop meaning what they meant. Errors in a car log are invisible — nothing turns red, the MPG is just wrong. |
If your spreadsheet has survived a year and is current, it is working — keep it. If you are reading this because your last three fill-ups are on receipts in the door pocket, the tool is the problem, not your discipline.
Keeping an exit
Whatever you use, the test is whether the data can leave. CSV is the format that survives: it will still open in 2040, it is not owned by anyone, and every serious tool reads it.
- Keep the ISO dates (
2026-03-14). Locale-dependent dates are the single biggest cause of scrambled imports. - Put units in headers, never in cells.
Volume (gal), not11.4 gal. - One row, one event. No merged cells, no headers repeated mid-sheet, no blank spacer rows.
- Export a CSV copy once a year even if you never leave — a backup that does not depend on the app that made it.
These templates import into Carvico as-is
The two files above use the column names Carvico's importer recognises, so if the spreadsheet ever gets old, the move is: export CSV, tap Import, review the preview, done. Units and currency are detected automatically, decimal commas included, and every row is shown before anything is saved. The same importer reads the CSV exports of Fuelly, Simply Auto, Drivvo, Fuelio, aCar and Road Trip MPG — see the Fuelly and Simply Auto guides.
Questions
Will these open in Google Sheets and Numbers?
Yes. CSV is plain text — File → Import in Sheets, or double-click in Numbers. Save as .xlsx or .numbers afterwards if you want formatting to stick, but keep exporting a CSV copy for portability.
Can I use these for metric units?
Yes — change the headers to Odometer (km) and Volume (L) and keep the numbers consistent. The importer reads the units from the headers, so getting them right is the whole job.
What about multiple vehicles?
One file per vehicle beats a "vehicle" column: filtering, formulas and imports all stay simple, and you can hand one car's history to its buyer without sharing the rest of your garage.
Should I log every fill-up or just some?
Every one, including partials, or the MPG math breaks and your fuel-spend totals understate reality. Completeness is what makes a log worth keeping; a partial record answers no questions reliably.
When the spreadsheet gets old
Carvico imports it in one tap, then keeps logging down to a receipt scan — odometer, volume, cost and station read straight off the paper. Data stays on your iPhone and your own iCloud, exportable to CSV any time.
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