This seems to have turned into a bit of a witch hunt against BMW when it is a case of one person’s experience of one variant of one car and one dealer.
When I went looking at the X1 I was given the usual round the block test drive, as soon as I returned the salesperson offered an extended drive. I used the opportunity to drive the car on a hospital visit. I was able to test if my scooter could fit in the boot, a no brainer test really, because if the scooter didn’t fit the car wouldn’t do. I was given a top of the range x-line (full leather) I knew I couldn’t afford an x-line so knew that there was stuff in and on the car that I would not have on mine. I was able to drive on motorway and dual carriageway from Peterborough to Cambridge and return on rural roads. Personally I found the seats not to be a problem on this variant which is the same as the OP’s. The OP goes on to mention that he test drove in an older model than the one he bought. This is not a new model, it is a facelift, i.e. a few cosmetic and equipment changes, so nothing that would drastically change the dynamics of the ride or handling of the car. The OP did mention that the car he test drove felt different to the car he bought and suspected that the test car had the adaptive suspension but couldn’t prove. The SE variant he test drove would have had 17″ wheels, not the 18″ wheels as fitted to the x-line as standard. There’s quite a difference in ride quality between them.
All in all we have a large choice of cars on the scheme from a huge number of dealers, if one dealer doesn’t give you what your looking for then go elsewhere. I live in the middle of the countryside so all dealers are at least half an hour away but that wouldn’t stop me going to say Heathrow/Lincoln/Northampton (all more than 90 mins drive) or even further afield if I did not get the service required. All our circumstances and needs are different, there’s no use blaming the cars or manufacturers if their car doesn’t suit our needs we only have ourselves to blame if we make the wrong decision.