Originally Posted by SamS
It is my understanding that US EPA does not consider stop/start when determining fuel economy.
I paid for my '12 E92 M3, and there was definitely a $1300 gas guzzler charge.
That's my understanding as well - US EPA currently doesn't factor in improved fuel economy due to stop-start in their current test cycle, however, I believe that is supposed to change at some point in the future.
Also, I believe the GGT is not based on the EPA city/highway published mpg but on some other "average" mpg rating.