Trouble is, describing this as 'product placement' is somewhat of a misnomer. Product placement is where a manufacturer pays a production company to feature its products in productions as a form of subliminal advertising. If this was not placed in the programme by B&O or a dealer, then it isn't product placement. After all, any authentic domestic scene would have to feature a tv or stereo of some make in the living room wouldn't it?
Similarly, members of a cast would probably drive a car in a programme but unless paid to do so by the manufacturer it wouldn't be product placement.
After the 'Inspector Morse' series, if only the Mk2 had been still in production, it would have done wonders for sales!