Chassis numbers.

The chassis number is the one thing on the car that was never meant to be replaced. It is the first thing anyone asks you for, and the last thing anyone can check. We had a decoder here. It read numbers against three tables nobody had sourced, and it turned down one of its own worked examples, so we took it down. This page is what stands in its place: where the number is, what its parts are, and what a decoder would have to cite before it said a word.

What works today

What is a concept

The decoder that stood here has been withdrawn. It matched numbers against three tables we cannot cite, and it rejected one of the three examples printed underneath it.
Nothing on this page reads a number. There is no box to type into, and no result to get.
A chassis number is a record of what left the factory. It is not proof of what is in front of you, and VWX will not say that it is.

Where the number is.

Reference the data plate on the chassis plate or frame tunnel.

Where exactly depends on the family and the year. On a Beetle it is stamped into the frame tunnel under the back seat and repeated on the plate; on a Bus it moved more than once. Look for both, and photograph both before you clean anything.

What the number is made of.

A chassis number is two things joined together. A leading group, which the factory used to say what kind of vehicle this was and roughly when. Then a sequence, which is a position in a production run and nothing more. That is the whole of it.

The leading group: What the factory called this vehicle.
The sequence: Where it sat in that run. On its own it dates nothing.

Every glyph above is a placeholder. We are not printing a chassis number, invented or otherwise, because a number that looks real gets copied, and a number that gets copied ends up in someone's paperwork.

Which leading group belongs to which model, how many glyphs each group runs to, and which years changed the shape of it — that is exactly the part we cannot cite. Which is why there is nothing to type into on this page.

What we withdrew, and why.

Three tables sat behind the old decoder. None of them named where it came from. Here is what was in them, so you know the size of the hole.

Eleven type codes.: Enough to cover Type 1, Type 2, Type 3, both Ghias and the Thing, and nothing to say who wrote the list.
Fifteen model years.: The table began at 1965 and stopped at 1979, while the page above it offered to decode from 1949. Two of those numbers cannot both be right.
Nine plant digits.: Wolfsburg through to Australia, unsourced, and applied to every family alike.
A production period.: Built by subtracting one from the model year and printing August to July. That is an assumption with a template around it, not a record.

When it turned a number down, it told you a check had failed. No such check was ever run. There was no arithmetic in it at all — only three lists and a match.

Written example — not analysis output

What a sourced note would read like.

The number stamped on your frame head has the shape the factory used for this family. The leading group is the one recorded for the sedan. The rest is a position in a production run.

Source: the factory chassis-number schedule for this family, named here with its edition, so you can go and disagree with it.

What this does not tell you: whether the number was stamped when the car was built, whether the plate belongs to the frame it is riveted to, or whether the engine behind it is the one that left with it.

That is the whole of what a decoder could honestly say. We would rather print that than a year in bold type.

Envisioned

A decoder that names its source before it names a year.
A plain "we do not hold that" for every family, year and plant we cannot cite.
The tables published as reference you can read, with the edition they came from.
A number you can look up without it being kept.
VWX will not authenticate a vehicle, and will not share anyone's contact details without their consent.

Tell us what you think

Which numbers do you need decoded?
What would you need to see before you believed a decoder?

Concept

Matching numbers.

"Matching numbers" is two words doing an enormous amount of work in a classified advert. All it means is that the numbers stamped on the car agree with each other and with what the factory recorded. We had a checker here that said they did, with a score attached, on data covering two families and a handful of years. The score could beat its own ceiling. This page is what is left when you take the score away: which numbers to write down, where each one is stamped, and what a checker would have to show you before it was worth anything.

See the idea