The Bloodhound SSC (which stands for SuperSonic Car) aims to break the speed record for land (and air), reaching speeds in excess of 1000 mph. The current record is 763.035mph, just above the sound barrier, set in 1997. The attempt is slated for later this year.
What constitutes a legitimate speed record is not simple and requires that many tough conditions be met, including what constitutes a land vehicle, which is defined as a:
Vehicle propelled by its own means in constant contact with the ground (or ice), either directly by mechanical means or indirectly by ground effect, and the motive power and steering system of which are constantly and entirely controlled by a driver on board the vehicle.
To minimize the effect of tail winds, the testing conditions require two runs in opposite directions over a measured distance within the space of one hour. The rapid accelerations and decelerations involved will cause the driver to experience forces of 2.5g and 3g respectively, which means the driver will have to train hard to avoid blackouts.
The BBC has provided an interview with the chief engineer on this project who describes the technology of the car.