Brochure talk Think about the doors, glass, wiper motor, window motors, most of the dashboard, heater matrix/fan, bonnet release mechanism, door locks, airbags, seat belts, fuel tank... Thousands of boring parts you don't see come off the shelf.
Sure the engine, suspension, and body bits make a big difference to how it drives but do they really cost £17k more to make than those bits on a 335i ?!?!?
Probably not far off it I would imagine, think about the engineering costs of creating a car like that plus there is also a bigger premium that comes with the M badge. Folk on here have spent a lot more than 17k on their 350z to try and squeeze out 400 bhp and alter the look of it.
R