help with the rules ? kit car ? keeping the plate

With a rail you'd need to keep the chassis of the Beetle. That seems to be interpreted as the main spine plus front and rear suspension mounting points - ie everything less floorpans.

Paul H

How do kit car builders get around these problem ? Dax or Westfield etc ..

I've had an inquirey from some local about building a road car that. Looks like a cigar racer with a shark nose front end some thing like this crossed with formula vee chassis

To keep a Beetle identity you need to use all the chassis including the floorpans. Doing this you also avoid IVA

Try the Association of Car Enthusiasts website, there's a fair bit of info there and look at the IVA manual which is available to download.
As far as I remember any kit car now has to be IVA tested. If you've used all the mechanical bits from one car you should retain it's reg but you still need the test. If however you rebody a car using it's original unmodified chassis then you don't need an IVA test, just an inspection at the DVLA local office to confirm the cars ID. It gets classed as a rebody, you get a new logbook with the vehicle make of your choice on it. You have to think of something that isn't already trademarked. An example would be a long wheelbase beach buggy, no chassis mods so no IVA, a short wheelbase buggy does need to be tested because the chassis is shoertened. The DVLA requires a vw chassis to be complete with floorpans to count as umnodified, the spineand suspension mounts on their own are not enough.