MV6 has lowered and stiffened sports suspension, which was favoured by Police forces. So many Police cars were called MV6 in the log book, as this was the nearest equivalent, even though in truth they were not exactly to Retail MV6 spec.
Yours being silver and with heated seats does not rule-out it being a Police car, may have been unmarked vehicle or top-brass transport (they like to keep their bums warm).
One thing to note about Omegas is that apart from the suspension twicks all models are mechanically identical, e.g. all 3.0L cars have same engine spec for the year so the MV6 was identical engine and transmission wise to any other 3.0L. As said the only differences on the MV6 were suspension, wheels, and sports seats.