I entered the details exactly as they appear on the V5.
My Dakota is classed as PHGV so i opted for HGV as the vehicle type.
I have received acknowledgement of the application with a temporary sticker.
This is purple with the number 4 overprinted. I presume this relates to my Ducato being Euro 4.
I don't think it's that critical what you input, but to me it seems that comparison will be made between the V5 image and the values entered, so it makes sense if they're the same.