The facility you describe does not exist in UK so I'm sure there is no official BE translation for this. "Shared registration number" is probably the closest translation but, as that does not happen in UK, no British reader would know what you mean without further explanation, such as you gave above.

If that facility exists in the US or in another English-speaking country, maybe a LEO reader from such a country can help you further.

Although PLS says that that facility does not exist, there is something which is a bit similar, best illustrated, I think, by an example.

When you go to a garage to buy a car and you want to give it a test-drive, the motor trader will hang "trade plates" on it. These are supposed to cover the registration plates (although they usually don't) and permit the usage of the vehicle on the public road even if it is not technically "street-legal" at the time, having for example, no current vehicle licence disc (normally referred to as "road tax"), insurance in its own right or M.O.T. certificate.

Trade plates are also used when a vehicle is being moved by a motor trader from, say, one dealership to another.

My guess is that in the U.S., this mind of thing would vary from state to state.

The "trade plates" referred to by Joe W are, I beieve, the equivalent of the "rote Nummernschilder" which Jumbo describes (and they are also red!).

I do not think these are the equivalent of the "Wechselkennzeichen".

Ich denke auch, dass du das Konzept erläutern musst -- genau wie den meisten Deutschen den Begriff "Wechselkennzeichen".

OK. Sorry to be slow-witted, but I have got the point now. We do not have these things in the UK, despite my earlier mention of trade plates.

As we do not have them, we do not have a name for them, so the question now is ... why and for whom do you need a translation?

@ JoeW
As you worked out, not trade plates. This system is common in Switzerland: basically you take the plates off one car and put them on the other for a while, then swap back. Works out cheaper if you have, for example, an open-top sports car that you want to drive in the summer months only, or a second not-so-valuable car for the kids to learn to drive on...
"Einlösung unter Wechselschilder
Wenn Sie zum bisher eingelösten Fahrzeug ein zweites Fahrzeug unter Wechselnummer in Verkehr setzen wollen, werden folgende Unterlagen benötigt (Einlösung nur beim Strassenverkehrsamt möglich):"
http://www.stva.zh.ch/internet/ds/stva/de/die...
"If you buy a second car, you can obtain interchangeable plates from your Automobile Service. This allows you to drive two or more cars under the same insurance plan and on a single set of plates. Take note, however, that only the car with the set of plates is roadworthy: the other car has to wait its turn in the garage."
http://switzerland.isyours.com/e/immigration/...

@Marianne:

1) I agree with Jumbo's initial comment that "interchangable plates" sounds more like two or more plates which can be fixed on one car.

2) Registration numbers and number plates have nothing whatsoever to do with insurance (at least in UK).

3) "Roadworthy" is wrong. that edescription means that a car is mechanically fit and safe to be used on a road; not that it is authorised to be.

@PLS
yes, I'm sorry - a poor choice of site to quote. I was trying to find something to explain the system which is very common here, but I shall now leave it to those more expert than I am in this field - and just swap the plates over when necessary :-)

Es gab schon mal eine Anfrage dazu:   related discussion:interchangeable licence plates - Wechselkennzeichen

...would be my suggestion. You just *transfer* it from one car to another.

@Anne (gb): Sounds plausible enough, but don't you say "registration plates" instead of "licence plates" in Britain, at least in legal acts and official correspondence?

@Jumbo, @Anne,

Yes, "license plate" (not "licence plate") is AE.

"Number plate" is BE.

@Jumbo: Yes, we do. Sorry, I was led astray by the title of Sophil's link and concentrating too hard on how to convey the "Wechsel" here.

@PLS: Be aware that trade plates are not the equivalent of the "rote Nummernschilder" (Überführungs/Überstellungskennzeichen), because trade plate numbers identify the holder of the trade license rather than the vehicle they are displayed on, and they are not transferable between traders. The trade plate allows the motor trader and tester to carry out their business without the burden of registering and licensing every vehicle temporarily in their possession. There are analogous number plates in Austria, called "Probekennzeichen" or "Probefahrtkennzeichen", which do not exist in Germany, I think.

A "Überführungs-/Überstellungskennzeichen" can be obtained by private individuals, who wish, for instance, to de-register their vehicles, transport them to another country and have them registered there. Does such a facility exist in English-speaking countries?

@Andi: I agree with your description of the use of trade plates in the UK. Thank you for pointing out the correct use of "rote Nummenschilder" in Germany. I have misunderstood that ever since I have been living in Germany (only 17 years!).

To answer your question: Such a facility does not exist in the UK (I cannot speak for other English-speaking countries). I cannot see the use for it. When I came to live in Germany, I bought a new car in UK and it had a normal number-plate. I was told that the number itself was a special export one but its format was indistinguishable from a normal UK number of the time.