Sorry I know this post is now a little bit old but I came across it doing some research and have info that might be useful to others.
So the GTD is not on the motability site but is on the VW site, we went into a VW dealership yesterday and managed to get an amazing salesman, you cannot order a new GTD however there are about 100 GTD’s that you can have either on order or currently physical cars, the sales person searched the country and found us a car that matched what we wanted.. We were willing to travel to get the car but luckily the car was being built next week and was part of a chain of other dealers one of which was not too far away so the salesman called the other dealership (Not same chain) and talked the salesman through there giving all the details of the car and we ordered it and its being diverted from the dealership it was going to to the one nearer us.
If you want a GTD or any car that is further away they cannot do it over the phone however the salesman told us of a work around, if you call motability, do the application with them then phone the dealership back up and give them the info then you don’t have to actually go to the dealership to order, just to collect.
There is extremely limited stock and it is going fast but it is still possible to get a GTD.. I have to say the VW salesman was awesome, he ended up giving the sale to another garage but was still super helpful along with another salesman while we were waiting for the motability specialist salesman. This was a world of difference to our Ford experience when we got our last motability car where we felt like second class citizens, our first dealer had no auto’s and said they would not bother getting an auto to the dealership for a motability customer, if we wanted to buy privately then they could but they don’t get the same commission, we had to go to another dealership that had an auto to test drive, we had to wait over 2hrs and they really didn’t want to deal with us and was the shortest test drive ever,.