I don't know if it is totally ridiculous to expect a new replacement vehicle. I actually empathise with the OP.
First point is, how do the inlet and exhaust camshaft sensors get so dirty on a brand new vehicle that after driving for < 100km causes the engine to run extremely hot, shut down and white smoke to pour from the engine bay?? Remember this is not a cast iron block, cast iron headed engine out of a 1971 XY Falcon that can handle high engine temps.
Is the 100% reliable fix to clean both sensors and refit to vehicle or do you continue to drive the vehicle, putting more kms on it and risk then being plagued with constant dealer visits to rectify this issue or other associated faults due to dirty camshaft sensors. This is a brand new car after all.
Secondly, it is not a big deal for the dealership to provide the OP a replacement new vehicle. I am provided with a loan car on every dealer visit whether it is for servcing or for any warranty claim no matter how big or small, so have had a few. I have had X3's, an e90 320i LCI M-sport wagon, numerous e90 LCI 320i's with innovations package, an X1 and a 135i M-Sport with Performance Power Kit (and even BMW Performance striping
). Every loan car has had less than 2000kms on it. I have had one X3 with 60 single kms on it. I almost felt bad for taking near brand new cars as loan cars, at no cost to me, for sometimes days on end and over the weekend, then proceeding to put hundreds of kms on them. So I asked the Service Manager how the loan car system works. He firstly told me not to feel bad. The service dept grabs on the whole "modestly" priced cars off the showroom floor. The service dept at my dealer has at any one time 5 x loan cars in use. As soon as any loan car clocks up 3000kms they are then sold as demo models. The dealership then assigns another new vehicle, which is in stock, to the service dept for use as a loan car.
The OP's car could easliy be swapped for a car that is to be assigned as a loan car before it is actually handed over to the service dept. The OP's car could then be assigned as the "new" loan car for use by the service dept and the OP provided with the new showroom vehicle which was originally destined for use by the service dept as one of their new loan cars. Remember the car has not been touched by the service dept and should only have delivery kms on it.
Most loan cars, in my experience have been e90 LCI 320i's of some sort and of differing option levels.
Assuming that the OP's dealer employs this loan car assignment process, a replacement new car for the OP could be provided by re-arrangement of some internal dealership paperwork. Probably as a trade in on the same type of vehicle with no change over cost or at least by some other means nominated by the dealer. Once a car is registered by the dealer it is considered a demo, with delivery kms on it, if not sold on prior and first registered in the new owner's name. Cost should be very minimal, if none at all for the dealer to provide a replacement new vehicle to the OP.
Buying a new vehicle is supposed to be an exciting, happy, fulfilling experience. If I am not mistaken, it sounds like this is the OP's first BMW. He at least deserves an unmolested example of one of BMW's "Ultimate Driving Machine". I would.