Ok guys listen to my experience today on this very subject.
I have owned a Modified Impreza that I then changed to a VX220 T. On both these cars I ended with 3 years no claims. I then changed my vehicle again to a Nissan Navara (don't laugh). Anyway..I have just sold the Navara and finally thought ok time to go get my skyline like I have always dreamed of. So last night I brought a cheap renault clio (don't laugh again) to get me to work and back and tied me over until my skyline arrives in 2 months time.
Ok now for the best bit...I rang adrian flux to get a new quote for my skyline when I get it and another for my clio....I was told that I have now lost my 3years NCD. Why I hear you ask...well aparently because the Navara is classed as a comercial vehicle you can transfer a car NCD to comercial no probs BUT!!! you cannot transfer them back so I will have to insure one without any NCD!
I am a little upset now as my dream car is out of reach because to insure both vehicles will cost me £2400.00 as I don't want use the skyline every day. £450 for the clio ( cost me £250 to buy) and £1950 for the skyline.

Thats with 5k limited mile as well!!!
So I am a little up s**t creek without a paddle!
But can some one answer how if I get points in one car they are carried across....How if I have an accident its carried across??? Basically anything to penalise you is carried across but anything for you is not!
Robbing b******ds thats all I can say worse than the IRS!!!