Right now the fastest production car (this excludes racing cars) is the Bugatti Veyeron, with a 0-60 time of 2.3 seconds or so. It costs a silly amount, however. The most bang for the buck is either the Corvette Z1 or the new Dodge Viper. There are also custom tuners (like Hennessey for the Viper) that make them even faster. The fastest car, ie. the land speed record, is held by the ThrustSSC set in 1997. It broke the sound barrier (Mach 1) on land. Holy cow.