BMW320d sport plus convertible

Isn't this already the "old" version? Guy over the road from me has a new 3 and it's got a totally new front end look to your pictured car.

Possibly the reason for a large price reduction? I suspect you will always feel like slight second best when the facelift cab hits the road.

I have driven a few new 3 series various models and I have to say I always feel a tad cramped in and claustrophobic in the drivers seat. Maybe a bit different in the coup cab, which I haven't driven.

Like BMW generally and must say the latest 5 is a real masterpiece both to drive and be onboard. Would really consider one for my next car.

My last car was an E92, nice car let down by a poor cabin

The car pictured IS a pre-facelifted model, that is, it is effectively already old. You should have established that fact for yourself, or at least been far more curious as to reason for such the huge discount. Car salesman love people like you, putty in their hands as they pocket their bonus.
Check out how the new shape, for subtle though the differences they result in a much sleeker shape. Consider also that whilst the 320d is the best seller, it's still a fairly basic spec., has to work hard to haul a heavier version of the saloon, and do you really want the whiff of Derv when the roof is folded. Note the colour is ordanary solid white so you don't even get a nice smart metallic colour for the price.
No BMW cabriolet is ever going to be a class act. Well engineered and a delight to drive they may be and for few months they may impress, but too many are owned by 'ladies that lunch', well to do wives, iffy business sharks and then worse you begin to see them slightly down at heel parked at the kerb in slightly run down suburban estates.
Finally ........ do you REALLY want to be a BMW driver? These days because of the arrogance of the dealers and the owners the brand has more stigma than credence.