 If you are considering buying one of these cars, be aware that there is an design/engineering issue which causes a vibration between 55-70mph.  Ford cannot figure out the problem, many owners are having to leave their cars at the dealers for months waiting for parts to be ordered which may/may not be able to fix the problem.  IF you are considering buying a S550 mustang (2015+) MAKE SURE you drive it to 55 MPH-70mph and pay attention to vibration.  It may be subtle, it may be drastic.  This isn't 1 in 50 this affects, its more likely 1 in 2 that this problem exists in.   Reference: http://www.mustang6g.com/forums/showthread.php?t=15990Recommendation: as pretty as they are, do not buy an S550 Mustang until Ford steps up and reengineers a solution to this problem. This may mean a completely new driveshaft, differential, and output flange for all users - BUT wait till Ford releases a TSB before you consider buying one of these.