I’ve been in and out of BMW M5’s and 550i’s and because of my vanity, I couldn’t go with a high performance sleeper. I needed something that shouted “Car Guy!”. If you are more secure than I, give some thought to a BMW 550i with a 400hp twin turbo and an old fashioned 6 speed manual transmission. The Mustang GT will never see you coming.  Here’s the CarMax link – if it’s dead the car is being transferred, or on hold/sold.
