I like to think that everybody involved with a new BMW be it the designer, engineer and the marketeer are very much a team effort.
Everybody is allowed their opinion. Basically what you begin with is a jigsaw and you are trying to fit all the pieces and like you do with a jigsaw you evaluate each piece to determine whether it fits.
That is exactly what we do on a Monday morning. Because we have several options or pieces some that fit and some that don't. So we evaluate each piece whether involving engineering , powertrain or even design to submit the proposal to the BMW board. But each evaluation involves protototyping so they design and build prototype engines , suspensions etc to see what is possible and entirely suitable for the car.
Every solution is developed and tested and the results published and the engineers present their case. Every car prototype presented is not the final version , each idea goes under a stage of progression on the results of feedback , BMW like to challenge their designers , engineers , marketeers , associates etc... And that is why BMW is top of their game.
And when you think across in Ingolstadt they just want to beat the BMW.
A final sign off could be a "Frankenstein" prototype - using multiple solutions from each stage of testing but the finished result always speaks for itself.