The traffic lights must be farther apart in Colorado. ;-) I get ~17 mpg with a mix of stop/go. My commute of 15 miles to the office which is 75% freeway driving and 25% stop/go yields me over 20mpg.
Commuting back and forth to work with a mix of stop-and-go highway in traffic i got an average of 11.4 mpg and when i drove more spiritedly it when to 10.4 mpg. Now i then said let me put it in p400 and use D2 and D1 which means it short shifts at like 2500 rpm, the result in addition to wanting to kill somebody was 12.8 mpg but really not liveable. So it is a massive gas guzzler not to mention the expensive castrol 10w-60 that is only available from the dealer at a tune of $16.95 per quart and it ate 1 quart every 800 miles consistently.
Finally the SMG, love it or hate it, i initially loved it until it became less smooth and started kicking into 1st from a standstill if i did not have the foot on the brake after coming to a stop, something akin to releasing the clutch suddenly, clearly a glitch that the dealer could not fix and did not go away despite the software update.
Mind you, i took it yesterday for a spin and it is exhilirating in S6 P500S DSC in MDM or off, the V10 screaming like a banshee and the transmission literally blindingly fast with F1 sounds, lovely, until you realize the car is still a 4000lb sedan so i were in Europe or somewhere where there are no speed limits and had a private oil well and refinery, then it would be fine. As it stands the car does not make more sense than a 550i or for that matter a 530i in the US.
I don't know i guess it was a phase and i outgrew it, the SMG finally pissed me off so did the oil and gas unreasonable consumption and which is ridiculous, i mean it's not a V12 ferrari or lambo to overlook something like that.
In the end, i will miss it but a single trip in the 997S on a few twisties and that unruly backend and i realize that it is probably best to compartmentalize, get a sedan that is comfortable for everyday use and get a dedicated real sports car.
I am sure that the M5 is faster that the 997S, in fact i think after the initial launch where the 997S may be a smidge ahead, the M5 reels it in no time, and just like in the case of my previous M3, both M5 and M3 are probably faster around a track than the 997S when driven by mediocre drivers, both M's are ridiculously easy and safe to go fast in.
Somehow BMW lost the important fact that drivers need feedback and emotional communication with the car, and sad to say this is where the new M-BMW's fail and Porsche rules.
I got frustrated with the M5 and thus the switch, maybe i am fickle and i will only find out in a few months if i get bored with the elfer but for now this is how i feel. My goal now is to master (if that is possible) the Carrera's handling strengths and quirks and have fun listening to that flat-6 reminding me of LeMans in the 70'-80's.
I think it is the same story when comparing the Z4M and Boxster S. BMW need more M-motional vehicles, like the e30 M3, not overweight fat barges with ridiculous consumption, and half-baked transmissions. The new 6-speed M5 is likely to also be a disappointment as you cannot completely disable traction control...
Hope this helps somebody out there and btw for the guy who has a kid on the way, my 6-year old twins seem to enjoy being in the back seats of the Porsche more than they do being in the back seats of the M5. Go figure...