uberstang1

Basic knowledge, auto makers wanna advertise the best fuel economy and fuel price possible, if it came from the dealer calling for 91 theres a reason (this case the compression ratio) because if there was anyway for it to be good on 87 it would of been.

GalaxiePete

Well just to throw this out there... The new 5.0 L is 11.0:1 compression and runs on 87 Octane. Yes there are reasons manufacturers do it - not what we always think though.