Gotta agree.....sort of.
I guess they mean inform the DVLA that the vehicle has been exported as that is the only way you don't need a UK mot or road tax to be legal...
Next bit is.....what country have you gone to.... as you now come under their laws... some dont even require mot or tax.
That site linked is over 7 years old,so no good now.
You need a carnet de passage to do what that link thinks is legal.
As a long term overlander I know taking your vehicle out of the UK is a can of worms.
1 It is illegal to take your vehicle out of the UK while on a SORN although people do do this.
2 You can take your vehicle out of the UK as a temporary export for periods of up to one year. As has been said you must have a vehicle that complies with UK rules to be driven on the road
3 If you go to the EU you cannot use a vehicle in one country for more than 6 months. If you move to another country within 6 months then you can start on the 6 months limit again. Otherwise you have to get residency and register the vehicle in that country.
4 For entry into countries outside the EU, each country has its own rules as to how long you can keep your vehicle in that country as a temporary import. The period you are allowed may not be the same as you are allowed on your visa free or visa based entry.
5 The paperwork you need to take a vehicle into a non EU country varies. The Carnet de Passage has been mentioned. This makes entry into countries that accept it quite easy but setting one up can be expensive. If you need one you can get it here
Carnet de Passage en Douanes (CPD) - CARS
The AA and RAC no longer issue these
Other countries issue a TIP or Temporary Import Permit. These are usually obtained on the border.
6 If you take your vehicle out of the UK for more than 12 months then the DVLA deem your vehicle to have been permanently exported. Since you cannot get an acceptable MOT etc there is no way you can avoid this. So it is easiest to declare the vehicle permanently exported by completing part 11 on the V5C when you exit the EU (doing this keeps the UK EU wide
insurance cover in force until the last moment) Digitise and print out an exact copy of the V5C before cutting it up. Reimporting the vehicle is a bit of a hassle but not too difficult - can explain more if needed to anyone interested.
7 The DVLA have no interest in the vehicle once its permanently exported although they do keep the records on file. This means no MOT, no UK
insurance and no road tax.
8 Having permanently exported the vehicle if you are overlanding and not emigrating to one particular country then the vehicle becomes stateless. The only way overlanders deal with this is to continue to use the V5C as though the vehicle is still registered in the UK. This is because it would otherwise mean reregistering the vehicle for every country visited. The RAC used to reissue the 12 month Carnets de Passage in these circumstances but I have no idea whether the new company issuing Carnets will do this. Countries using TIPs don't seem to have a problem with temporary imports.
9 The issue of a stateless vehicle has been raised with the DoT without any sensible answer.
