I can confirm that the Mercedes-Benz V 220 d Marco Polo, WDF44781323480847, is correctly classified at the DVLA as a MPV.
The Marco Polo is a M1 car and only vans (N1) can have the classification of Motor Caravan.
(The VED would be cheaper if we could classify the Marco Polo as a Motor Caravan.)
The Association of British Insurers have issued an insurance rating for the V220 d Sport Marco Polo and the ABI code is 32132322. This ABI number should help your Insurance company the correct vehicle from their database.
I've just acquired a Marco Polo V250d demonstrator. Its V5C shows the Taxation Class as "Diesel Car" and the Body Type as "MPV". I tried to insure it through both the Caravan & Motorhome Club and the Camping & Caravanning Club (from whom I had quotes for a VW Cali when I owned one) and they both declined to quote on the grounds that an MP is not a motorcaravan. One suggested that I got the vehicle reclassified as a motorcaravan! Other insurers quoted for it as a car, including Safeguard (who specialise in motorcaravans) and from whom I got the best quote after mentioning Marco polo club membership.
I had the same experience with a couple of companies who I don’t think understood what vehicle the MP is.
I eventually added my MP to my existing car insurance policy with Aviva on their multi vehicle policy. The additional cost was minimal but gives me the peace of mind of being with a decent company