Audi VIN decoder: the VIN, and the sticker in the trunk

• Model year, model and body class as filed with NHTSA
• Engine displacement, cylinder count and fuel type
• Drivetrain — front-wheel drive or all-wheel drive
• Restraint system fitted at the factory
• Country of manufacture and the assembly plant
• Open safety recalls against that exact vehicle

Audi, in common with the rest of the Volkswagen group, describes vehicle equipment using PR codes, and prints the complete list for each car on a sticker attached to the vehicle. It is genuinely the most useful piece of paper in an Audi.

1. 1Open the trunk and lift the floorThe sticker is usually under the trunk floor covering, in or beside the spare wheel well. This is the first place to look on nearly any Audi.
2. 2Check the service book if the sticker is missingThe same list is frequently reproduced in the owner's literature.
3. 3Photograph the whole stickerNot just the codes you recognize. The paint code is on it, and so is equipment you may want to identify later.
4. 4Ask a dealer if there is no sticker at allThe parts department can retrieve the build record from the VIN.

This is the Audi-specific point most likely to cost a buyer money through a wrong assumption. quattro identifies Audi's all-wheel drive as a marketing name, but the hardware underneath has differed substantially across model lines and generations.

Different systems behave differently in normal driving, split torque differently, and carry different service requirements and failure modes. A decode confirms the car is all-wheel drive. Which system it uses follows from the model and the generation, and it is worth establishing before you form expectations about how the car will drive.

• Establish the model and generation first, then research the system that pairs with it
• Ask about service history for the all-wheel-drive components specifically
• On a used car, listen for driveline noise and feel for binding at low-speed full lock
• Confirm all four tires match in make, model and wear — mismatches stress the system
• Ask whether any differential or transfer component has been replaced

Audi sits within a larger group and shares engineering across its sibling brands. An Audi model frequently shares a platform, and often an engine, with vehicles wearing other badges.

For an owner this is mostly good news. Mechanical parts availability is better than a premium badge would suggest, independent specialists who know the group's hardware are widely available, and known faults are documented across a larger population of cars.

Audi identifies engines by letter codes, and the code is what a parts department and a specialist workshop will ask for. The eighth VIN character identifies the engine as built; the code itself is stamped on the engine.

Most modern Audi gasoline engines use direct injection, which brings a maintenance consideration worth knowing before you buy rather than after. Because fuel is injected into the cylinder rather than the intake port, the back of the intake valves is not washed by fuel, and carbon deposits accumulate over time.

• Ask whether intake cleaning has ever been performed, and at what mileage
• Symptoms include rough cold running, misfires and gradually worse economy
• It is a maintenance item on these engines rather than a defect
• Ask about timing component service history — this varies by engine and is not optional
• On a turbocharged engine, ask about oil service intervals and which oil was used
• Get the engine code and research that specific engine, not the model

Audi's performance variants carry substantial premiums, and the badges are inexpensive to buy. On these cars the difference between the real thing and a well-dressed base model is thousands of dollars.

The VIN and the PR sticker together settle it. The engine, brakes, suspension and drivetrain hardware are all recorded, and none of it can be added to a sticker printed when the car was built.

• Confirm the engine from the decode and from the code stamped on the engine itself
• Check the PR list for the brake and suspension specification
• Verify the interior equipment matches what the sticker records
• Ask about modification history — these cars are remapped frequently
• Ask about track use, which is excluded by most warranties
• Get an insurance quote before committing; performance variants can surprise

Recalls attach to VIN ranges rather than models, and campaigns sometimes span several group brands at once because the affected component is shared. NHTSA's free lookup answers it at VIN level, and the remedy costs the owner nothing regardless of how many owners the car has had.

1. 1Decode before you travelConfirm model year, engine and drivetrain match the listing.
2. 2Find and photograph the PR stickerTrunk floor or spare wheel well. It settles every equipment claim at once.
3. 3Get the engine code and research that engineNot the model. Engines carry across the group and the documented experience is engine-specific.
4. 4Ask about carbon cleaning and timing serviceOn a direct-injection engine both are real maintenance items with real costs.
5. 5Check all four tires matchOn an all-wheel-drive car this matters mechanically, not just cosmetically.
6. 6Run the free recall checkInstant, free, and the remedy costs nothing.
7. 7Use an independent group specialist for the inspectionCheaper than a dealer and generally better informed about the specific engine's weak points.

The specification the VIN describes is also a forecast of your maintenance spending. Larger engines, all-wheel drive, adaptive suspension and large brakes all deliver what they promise and all cost money to keep working.

• Adaptive or air suspension is excellent when working and expensive when it is not
• All-wheel drive adds components and adds service cost
• Large-diameter wheels mean expensive tires and more damage risk from potholes
• Turbocharged engines reward strict oil service and punish neglect
• A complete service file is worth more here than on a mainstream car
• Budget for the generation and engine, not for the badge