This thread has been very informative and also rises lots of doubts...
I've been reading the thread for quite a while and decided to join the forum to post a little contribution on my own experiment on the water temperature over regular driving.
It's been like 4 days that I've been monitoring in detail the water temp and this observations are very consistent, my 335i seems to "want" to run at coolant temperatures on the range of 99-103º C on regular driving, no matter the speed. I registered temps of 101º C driving steady @ 70mph on the Florida turnpike or regular street speeds peaking at 105ºC at lights or stops, haven't seen anything beyond that and drops inmediately to the average as soon the car is in motion.
However, the interesting thing is that when I push the car flooring it for a brief amount of time and getting reved up (just enough to not become the crazy guy on the street) the water temperature drops significantly. Driving on the highway (turnpike speed limit 70mph) to 55mph and sprint to 80 mph and drop to 70 mph, the indicator will show a drop in a matter of seconds from 102ºC to 94ºC and some times as low as 87ºC.. Temp will again raise to the average stated before as "old lady style driving" resumes. Same behavior at street speeds, with less temp drop but the combination of full throttle and higher revs reproduces it.
Seems there is some complex coolant management going on...
I'm taking the car to a hooked on driving event at homestead speedway and will keep an eye on the temp to report.
Last edited by mixman; 04-26-2012 at 11:57 AM.