Equipment added to the X models includes satellite navigation, reversing camera, parking sensors, HID headlamps with daytime running lamps, keyless entry, sports pedals, aluminium scuff plates, five-spoke 18-inch alloy wheels, a rear lip spoiler and 'X' badging - features totalling more than $9000 of value.
Both models are also available with an exclusive red perforated, semi-aniline leather-accented interior trim with red stitching.
The 153kW/252Nm 2.5-litre V6-powered Lexus IS250X and 233kW/378Nm 3.5-litre V6-powered IS350X are available in White Pearl Mica, Silver, Mercury Grey, Starlight Black Glass Flake and Vermillion Red Mica paint finishes.
The special edition models will be available until March 31, provided stocks allow.
The new Lexus IS, unveiled at the Detroit motor show in January, is due to arrive in Australian showrooms in the third quarter of 2013, with the IS250, IS350 and new petrol-electric IS300h versions of the third-generation Lexus IS set to make up the range.