What is a service history and treatment log?
A service history — also called a treatment log — is a chronological record of every treatment a vehicle has undergone: the product used, the area treated, the date and time, the installer who did the work, and any images documenting the result. Its purpose is simple: make it possible to prove what was actually done to the car, without anyone having to rely on memory — not yours, not the customer's, and not the manufacturer's.
A good treatment log functions as the car's digital service book, and it underpins warranty claims, customer trust and resale value alike.
Why does a treatment log matter for warranty claims?
The treatment log serves three critical purposes — and they affect you as the detailer just as much as your customer as the car owner:
- Warranty documentation: If you can document that service intervals have been observed, your warranty claim stands markedly stronger against the manufacturer or distributor. If you cannot, you risk the claim being rejected — regardless of how correctly the treatment was carried out. Most premium coating warranties require a service visit every 12–24 months to stay valid, which is exactly the interval a treatment log lets you keep and prove.
- Customer experience: A customer who can see the full history of their car — what was done, when, and by whom — feels well looked after. That builds loyalty and makes it the natural choice to book the next service visit with you rather than another shop.
- Car resale: A documented service history increases credibility and sale price, because the buyer can verify that the car was actually treated correctly — not just take the seller's word for it.
How does a documented service history affect a car's resale price?
A documented service history can noticeably increase a car's resale price, because it removes the buyer's uncertainty about what the car is protected with and whether the warranty is still valid. Our own data from more than 200 centres shows that cars sold with a documented PPF and coating warranty achieve on average 3–8% higher sale prices than comparable cars without.
For your customer, that means a treatment log is not just documentation — it is a selling point on the day the car moves on. For you as the detailer, it means the service history is worth mentioning actively as part of the value of your work, not just as an administrative formality.
See our guide on what happens to the warranty when a customer sells the car, including how the warranty transfer itself works in practice.
What should you log for every treatment?
A useful treatment log covers, at minimum:
- Product name and manufacturer
- Treated area (e.g. "Full undercarriage including wheel arches")
- Date and time
- Installer name
- Before/after images
- Any notes (e.g. "Mark on boot lid noted on arrival")
That last point — notes and images taken at intake — is often what settles a warranty or liability dispute later. A short intake photo routine, which takes most shops two to four minutes per vehicle, gives you and the customer the same record to look at if doubt later arises over whether a scratch or mark was already there.
How long should a service history be kept?
There is no single fixed, legally mandated retention period for a treatment log — the rule of thumb is to keep it at least as long as the warranty is valid, and ideally for as long as the customer owns the car. Coating warranties typically run 1–2 years at entry level and up to 5 years or more on multi-layer packages, while PPF warranties often run even longer — so a log kept for only a couple of years risks missing exactly the documentation a warranty claim or car sale needs years later.
In practice, that means a treatment log should be stored digitally and permanently, rather than in a folder or on a single technician's phone, where it effectively disappears the moment that technician changes jobs or upgrades their phone.
Digital vs. manual: Which method holds up in a warranty dispute?
Manual — an Excel file or a Word document — is better than nothing, but it is hard to share, easy to delete by accident, and nearly impossible to verify if a manufacturer or customer questions it. There is no timestamping, no backup outside your own computer, and no way for the customer to access the history themselves.
A digital system like sevv logs every treatment automatically as part of the visit workflow: the installer uploads images directly from their phone during the job, and each entry is timestamped and tied to the specific vehicle rather than to a person or a single file. That makes the record legally stronger than a loose spreadsheet — much like a digital warranty certificate with a timestamp and electronic acceptance stands stronger than a piece of paper simply handed over.
How does the digital service journal actually work?
The digital service journal is the combined, shareable version of a car's treatment log — accessible via a unique link or QR code, without the customer creating an account or remembering a password. Every vehicle gets its own journal token, tying the history to that specific car, so the link or code always shows the correct, up-to-date record — whether the customer scans it from a receipt, a Wallet pass, or a link in an email.
For the customer, that means the entire service history can be shown with a single scan — to a buyer, an insurer, or just out of curiosity. For you as the detailer, it means you never dig up an old job manually when a customer calls asking what was done two years ago.
Can a treatment log help you sell more maintenance work?
Yes — a treatment log is, in practice, the foundation for selling more maintenance work, because it shows exactly when the customer last came in and when the next service is due. Combined with automatic reminders built on the log's data, it can meaningfully raise the return-visit rate — our own data from more than 200 centres shows a 2–4× higher return visit rate for businesses using automatic reminders within the service window, compared with leaving it to the customer to remember.
In other words: the treatment log is not just insurance against disputes. It is also the data that makes a systematic maintenance and return-visit flow possible, instead of hoping the customer remembers to book again.
A documented treatment log is both your strongest warranty documentation and what typically raises a car's resale price by 3-8% — the same data serving two purposes.
Frequently asked questions about service history and treatment logs
Should I log a treatment even if the customer doesn't have a warranty?
Yes. Even without an active warranty, a treatment log is valuable documentation of both the product used and the work performed — it protects you if the customer is later unhappy with the result, and it gives the customer a reference point if the car is later sold or needs a fresh coating.
Can customers access their own service history?
Yes, with a digital system the customer can see the full history in their own portal, or via a shared link or QR code, without needing to ask the shop. That noticeably reduces the number of calls asking what was actually done to a car, since the answer is already available to the customer directly.
What happens to the service history if I switch systems?
It depends on the system — some allow export to formats like CSV or PDF, others do not. Always ask a vendor, before you commit, whether historical data can be exported or transferred, so you don't end up with a treatment log locked inside a system you're leaving.
Is a treatment log the same as a vehicle inspection report?
No. A vehicle inspection report documents a car's legally required roadworthiness, while a treatment log documents the cosmetic and protective treatments the car has received — coating, PPF, wrap and similar. The two complement each other but don't replace one another.
Can I use the treatment log as marketing to new customers?
Yes. A clean, professional service history — with images and clear documentation — signals a level of seriousness that is hard to convey verbally. Many detailers show, with the customer's permission, examples of their digital service journal to prospective new customers as proof of their working standard.
A treatment log that actually gets used — not just filled in and forgotten — needs a system that makes logging easier than skipping it. In sevv, that happens automatically as part of the visit workflow, and the customer gets access to their own digital service journal immediately. See what your customer gets access to, or get in touch to see how it's set up for your shop.