automatic gearbox was made available on 200Tdi models, new colours were added to the range (and the large 'compass and mountain' side decals worn by early Discoveries to disguise wavy panel fit around the rear three quarter windows were no longer fitted) and the 'SE' pack (incorporating alloy wheels, front driving lights, roof bars and a special range of metallic paints) was introduced as an option. A two-seater, three-door Discovery Commercial version, lacking rear-side windows, was later offered by Land Rover Special Vehicles. Before 1994, the Discovery was available with either the 2.5-litre 200 Tdi engine or the 3.5-litre Rover V8. Early V8 engines used a twin SU carburettor system, switching to Lucas 14CUX fuel injection in 1990. A 2.0-litre petrol engine from the Rover stable was briefly available in a model known as the 2.0-litre Mpi I4. This was intended to attract fleet managers, since UK (and Italian) tax laws benefitted vehicles under 2.0 litres. A combination of changes in taxation and lack of power for such a heavy vehicle led to the demise of this engine, despite its fitting to several Discoveries supplied to the British Royal family. One of these was notably driven by Prince Philip around Windsor Great Park, in his position as Park Ranger. The transmission was a permanent four-wheel drive system, with a high and low range transfer box, locking centre differential at the transfer box. Similarly to the rest of the Land Rover range, the handbrake acts on the transmission at the back of the transfer box, therefore locking the rear prop shaft or both front and rear prop shafts if the central differential lock is engaged. In Australia, the Series I launched in April 1991, available only as a three-door estate in 3.5-litre V8i guise with and and coupled with a five-speed manual gearbox. In October 1991, Land Rover launched the five-door body variant in base V8i and luxury HL versions. Both featured central locking, electric windows, headlight washers and heated door mirrors, with the HL adding alloy wheels, air conditioning, driving lights and an improved audio system. Furthermore, the Tdi engine became available, rated at and . In early 1993, a four-speed automatic option was added to the Australian range and the HL was discontinued. 1994 update In 1994, many changes were made to the Discovery. It reached some markets as the "Discovery 2"; the 200Tdi and 3.5 L V8 engines