I forgot to add, perhaps it's me but I felt I had more room in the 4/4. I know the tubs are the same so can't tell why.
Must be the lack of door pockets that gives you more room.
Ha Ha. Seriously, though both cars use the MX5 gearbox, it may be mounted further forward with the smaller engine, allowing the trans tunnel to be a tad narrower. Jays would know how they look on the production line, but I imagine he's having too much fun in Spain & Portugal to read this.