The project was overseen by Holden chief designer Richard Ferlazzo.

[1] The Efijy is based on a lengthened Chevrolet Corvette floor pan and features a 6.0 litre LS2 V8 engine with a Roots supercharger producing 480 kW (644 hp) at 6,400 rpm and 560 lb-ft of torque at 4,200 rpm.

[2] Power goes to the rear wheels through a rear-mounted 4-speed 4L60E automatic transmission with a limited-slip differential.

It rides on an air suspension system that lowers the car when it is stopped, and also has electronic instrumentation, including a multi-use display screen that disappears into the dash.

[3] Once it returned to Australia, the Efijy visited the National Motor Museum at Birdwood, South Australia, in February 2008 and again from December 2020 as part of the Holden Heroes exhibition along with 12 other significant Holden production and concept vehicles.