In 1989, The 911 was redesigned and the engine was increased to 3.6 liters.  4 Wheel drive was also added.   The Carrera 4 featured new brakes, transmission,suspension and more.  A self-adusting rear spoiler was added.  The Carrera 2 was introduced in 1990 and is almost identical to the Carrera 4 except it lacks the 4 wheel drive system.  The Carrera RS had a reduced weight and 10 more horses.