The cars available include the Lotus 49, Ferrari 312, Eagle T1G, Brabham BT24, and the BRM P115. There are also two fantasy cars to choose from, the Murasama and the Coventry - thinly disguised stand-ins for the Honda RA300 and the Cooper T86 (licensing issues precluded these marques from being included in the package). There is a 3rd party patch available to put the Cooper and Honda back on the starting grid if you wish.
Certainly the essence of GPL is the talent required to finesse these classic cars around the challenging circuits of the 1967 era. As in learning to play a fine musical instrument, you must have the patience and the light, smooth touch to get the most from these machines. You also need to have an intimate understanding of how the car setup parameters affect the handling. Luckily, there are several GPL web sites that cover these issues very well. Once you have a handle on how to drive these cars correctly the feeling of accomplishment is very tangible.
There are 11 vintage 1967 tracks included with the simulator. These include the high speed Monza circuit in Italy, the roller-coaster-like Mosport track in Canada, the tight streets of Monaco, and the original 14 mile long Nurburgring course in Germany. A number of GPL community members have created over 200 free add-on tracks for the simulation.
Other members of the GPL community have created graphic and audio enhancements to the cars that keep this simulator up-to-date.