Mach number temperature generally decreases with increasing altitude between sea level and , the speed of sound also decreases. For example, the standard atmosphere model lapses temperature to at altitude, with a corresponding speed of sound (Mach1) of , 86.7% of the sea level value. While the terms "subsonic" and "supersonic", in the purest sense, refer to speeds below and above the local speed of sound respectively, aerodynamicists often use the same terms to talk about particular ranges of Mach values. This occurs because of the presence of a "transonic regime" around M = 1 where approximations of the Navier-Stokes equations used
Ford Mustang Mach 1 5800 rpm (4-speed automatic)." While on paper the 305 hp (228 kW) ratings seem a loss when compared to the 1999 and 2001 SVT Cobras which produced 320 hp (239 kW), in practice the Mach 1 engine produced similar peak horsepower and substantially more torque. Further differences included the use of Ford's solid rear axle with a 3.55 final ratio (As opposed to SVT's Independent Rear Suspension) also the availability of a 4 speed automatic in addition to the Tremec sourced 5 speed manual. Factory steel "Box" cross section subframe connectors were also added to increase chassis strength for both