Wow! I was just looking into breaking the sound barrier and to do it on land at sea level you need to be going over 700mph!!! If that car is breaking the sound barrier it is definately the fastest land vehicle ever!
Values of the Speed of Sound:
One of the most common questions we receive is fow fast is the speed of sound, and as was pointed out earlier, there is no single value to quote. The speed of sound, also known as Mach 1, changes throughout the atmosphere based on the temperature at any given altitude. Probably the most important value to remember, however, is the speed of sound at sea level. Based on the standard atmospheric model, this value has been defined to be
1,116.4 ft/s
340.3 m/s
761.2 mph
1,225.1 km/h
661.5 knots
If you were to reach Mach 1, or "break the sound barrier," at sea level, the above speed is how fast you would have to travel in order to do so.