Back on topic with a plot twist: I thought that I would phone the Paris importer, Beaumont Automobiles, because they have a new P4 with a co2 list of 164 and my Carte Grise application is held up because they claim 217. Any way, the chap I spoke with asked if I had the 110 model, which I do and then explained that the reason my tax was so high is because I had had the discount, i.e. the £8000 worth of freebies from Morgan. I think that I am losing my mind. If anyone cares to check their site, the P4 is the one with led headlights.
The presence or absence of extras, other than sports exhaust and wheel/tyre size, has no impact on the CO2 level.