The Porsche series 964 is the internal name for the version of the model manufactured and sold between 1989 and 1994. It featured significant styling revisions over previous versions of the 911, most prominently the more integrated bumpers (fenders). It was the first generation of 911 to be offered with Porsche's optional Tiptronic automatic transmission". Type" 964 (nine-sixty-four) or simply 964 (nine-six-four) is in fact the internal code name for the car; the vehicle was badged simply as Carrera 2 (rear-wheel drive) or Carrera (all-wheel drive). Both variants were available as a coup, Targa or Cabriolet. The flat-six naturally-aspirated engine was a brand new one with a displacement of 3.6 liters. Porsche largely revised the suspension replacing the rear torsion bars with coil springs and shock absorbers. Power steering and ABS brakes arrive to the 911 for the first time and they were both made standard. The exterior bumpers and fog lamps became flush into the car, allowing for better aerodynamics. A new electric rear spoiler raised at speeds above 50 mph (80 km/h) and lowered down flush with the rear engine lid at lower speeds or when stopped. A revised interior featured standard dual airbags beginning in 1990 for all North American production cars. A new automatic climate control system provided superior heating and cooling. Revised instrumentation housed a large set of warning lights that were tied into the car's central warning system which alerted the driver to a possible problem or malfunction.