What is a car build sheet?

A factory build sheet (also known as a spec sheet or datacard) is the official record showing every option, package, paint code, and mechanical component installed on the car when it left the factory.

Can you check car factory options for free online?

There are free VIN decoders online for some brands, but they are not guaranteed to be accurate. Most only decode general model details and miss individual optional extras or UK-specific equipment packs.

How do you spot a fake M Sport or AMG Line?

Check the 17-digit VIN against the manufacturer build sheet. Genuine cars have specific factory option codes (like S337A for BMW M Sport or 950 for Mercedes AMG Line). If the build sheet says SE or Sport, the body kit is aftermarket.

Why do adverts often list the wrong spec?

Listing software frequently pre-selects options by mistake, or sellers confuse standard features with optional packs. Checking the VIN against manufacturer data is the only reliable way to confirm what the car actually has.

Buyer Guides2 September 2026• 6 min read

How to Find a Car's Original Factory Options & Build Sheet Using the VIN

From mislabeled advert descriptions to base cars fitted with replica body kits, here is how to find a car's genuine factory specification before you buy.

When you're looking at used cars on Autotrader, eBay, or Facebook Marketplace, optional extras make a massive difference. An M Sport Pro Pack on a BMW, a Bang & Olufsen sound system on an Audi, or a Premium Plus pack on a Mercedes can easily add £1,000 to £3,000 to the price.

The trouble is, advert descriptions are frequently wrong.

Sometimes dealers rely on automated listing tools that tick boxes by mistake. Other times, sellers guess what equipment the car has, or worse, fit cheap replica body kits to base-model cars and try to sell them as genuine sports models.

Tip: The only reliable way to know what a car came with from new is by checking its official factory build sheet using the 17-digit Vehicle Identification Number (VIN).

Why Adverts Often List the Wrong Spec

Spec mistakes happen all the time on used car adverts. Usually it comes down to three things:

1. Auto-populated listing tools

Dealership portals often auto-fill equipment lists based on a rough model match. If a base model shares part of its code with a higher spec, boxes get ticked automatically for options the car never had.

2. Changing option packs

Manufacturers change package contents between model years. A seller might assume a Mercedes has a panoramic roof because it's a "Premium" model, not realizing it was moved to "Premium Plus" for that year.

3. Sellers guessing

Private sellers and non-specialist dealers often assume standard features are optional extras, or list popular keywords like "Harman Kardon" or "Head-Up Display" just to attract buyers.

Fake M Sport and AMG Line Body Kits

Another common issue on used car marketplaces is cars dressed up with aftermarket replica body kits.

A seller buys an entry-level model (like a BMW 320d SE or Mercedes C200 SE), fits cheap replica M Sport or AMG bumpers, adds aftermarket alloys and badges, and advertises it as a genuine M Sport or AMG Line for £1,500 to £3,000 more.

Beyond overpaying for cheap replica fiberglass or plastic, this creates real headaches:

✕You don't get the actual upgrades: Genuine factory M Sport and AMG Line cars come with firmer sports suspension, upgraded brakes, different steering racks, and sport seats. A replica is still just an SE underneath.
✕Insurance issues: In the UK, aftermarket body kits count as modifications. If you insure the car as a standard factory M Sport and have an accident, your insurer can refuse to pay out for undeclared modifications.
✕Harder to sell later on: When you eventually sell or trade the car in, dealers and car-buying services like Motorway or WeBuyAnyCar run the VIN. The second the system flags it as an SE, their valuation will drop substantially.

Options That Are Easy to Miss or Misunderstand

While you can easily spot leather seats or a glass sunroof in photos, several popular options are hard to verify without checking the official spec:

Option	Typical Cost	Why It's Worth Verifying
Upgraded Audio (Harman Kardon, Burmester, B&O)	£800 – £2,000	Sellers sometimes fit aftermarket branded speaker grilles over basic factory speakers. Checking the build sheet confirms if the car actually left the factory with the upgraded amplifier and surround sound.
Heated Steering Wheel	£200 – £350	Dealers sometimes assume heated seats mean a heated steering wheel is included, but it's usually an optional extra or part of a comfort pack. In photos, the button is easily missed or buried in a touchscreen menu.
Adaptive Cruise Control	£650 – £1,200	Very commonly misadvertised. Sellers regularly confuse standard cruise control with radar-guided adaptive cruise. You need the build sheet or physical radar sensor to know for sure.
Keyless Entry	£500 – £750	Most modern cars have keyless push-button start, so sellers frequently advertise them as having keyless entry. Touching the door handle to unlock is almost always an optional extra.
Reversing Camera / 360 Camera	£350 – £850	Adverts often list a camera when the car only has parking sensors with an on-screen graphic. The build sheet shows whether an actual camera was fitted at the factory.
Folding Door Mirrors	£300 – £500	Sellers see electric mirror switches and list them as electric folding. Power-folding mirrors are often an extra or bundled into a convenience pack.

What Is on a Factory Build Sheet?

A factory build sheet (sometimes called a specification sheet or datacard) shows the exact configuration of the car as it came off the production line. It includes:

Engine and gearbox details: Confirms the exact engine code, power output, and gearbox variant.
Paint and interior codes: Confirms the original factory paint colour and upholstery trim.
Factory option codes: The manufacturer codes for every optional extra fitted:
- BMW: S-codes (e.g. S337A M Sports Package, S688A Harman/Kardon Sound, S322A Comfort Access, S248A Steering Wheel Heating).
- Volkswagen Group (Audi, VW, Škoda, SEAT): PR-codes (e.g. 1BE Sports suspension, 9VS Bang & Olufsen audio, KA2 Reversing camera, 8T8 Adaptive Cruise Control).
- Mercedes-Benz: SA Codes (e.g. 950 AMG Line, 810 Burmester Sound, 889 KEYLESS-GO, 239 DISTRONIC Adaptive Cruise).

Can You Use Free Online VIN Decoders?

There are free VIN decoders available online for some manufacturers, but they are not guaranteed to be accurate.

Most free decoders only read the basic 17-digit ISO VIN string. That tells you general info like the engine size, model year, and assembly country, but it doesn't decode individual optional extras or dealer-fitted packages.

Free tools also rely on scraped, third-party databases rather than live manufacturer feeds. They frequently guess specs or miss UK-specific packs like a Comfort Pack or Technology Pack. To see the genuine factory options list, you need data pulled directly from the manufacturer's system.

How to Check a Car's Build Sheet

At CheckThisReg, we pull official data directly from manufacturer systems using the registration number or VIN:

Check Factory Spec & Options

Get an official Specification Report or Complete Report straight from the manufacturer database.

📋 Specification Report

Full factory build sheet, original option codes, paint and interior codes, and production data.

⭐ Complete Report

Factory build sheet plus full digital dealer service history records and maintenance logs.

Check Vehicle Specification Now

Frequently Asked Questions

Where can I find the VIN number?

You can find the 17-digit VIN at the base of the windscreen on the passenger side, stamped on the driver's door pillar or in section 4 of the V5C logbook.

Can a local garage verify factory options?

Most local garages don't have access to proprietary manufacturer build portals without commercial brand licenses. Checking an official online report is much faster and cheaper.

Does an HPI check show factory optional extras?

No. Standard HPI checks look for outstanding finance, insurance write-offs, stolen markers, and mileage discrepancies. They don't include factory build sheets or optional extras.