It may be a nice example but a long standing advert always makes people wary, wondering why its sticking so long.
As you've asked, I'd say you may be a tad optimistic with the asking price. Whilst its' nice the spec isnt great. Within seconds of the advert I've noticed that it has no heated seats, no MFSW, no Sat Nav.
Ive just sold a better spec'd 57 plate 3.0Si for a bit under the £6k I advertised it at if that gives you a gauge. I think they have taken a tumble this year.
Also, advertising at £5400 I'd assume your looking for £5k (Thats what I'd try if I came to look) Therefore if you're not getting calls, why not try at £4995, so that you come in on the searches under the £5000 mark, but then stick firm at the £4995 once somebody has actually come to look at it and seen it in the flesh. Your first task is to get the phone ringing , then people stood in front of it. Agreeing a price is stage three.
Another point is that when advertising on the Forum, you are selling to the educated and open to the critics. If I were you, I'd re-advertise it with fresh photos and put it on Auto-trader or Ebay, where you may get someone less aware of the model variations, specs, typical problems and just sees it for what it is. - A Convertible BMW Sports car ...
Just my thoughts !
Good luck.