Bongo Fury

Hi. Just looked on the euro tunnel booking site (in readiness to book using my tesco vouchers.) They have changed it and for grey imports you are asked if it is a car or campervan . Well as my vehicle - Ford Freeda - is not the same as my previous bongo I felt some clarification was needed. As my vehicle is registered as a "car" I get the car price. Even though I told them that I had a solar panel on the roof and the roof was a rising one! I suppose it I had had the registered class changed then an increase cost would be charged. Just thought you ought to know if a trip through the Chunnel is planned.
I don't suppose it would save much but you could -for the duration of your trip change taxation class to the most less dear?
Yours ian G