The Toyota GZ engine family consists of a single model, the 1GZ-FE. This engine is used as the powerplant for the Japanese market-only Toyota Century limousine from 1997 onward.
The 1GZ-FE is a 5.0 L (4996 cc) V12 48-valve DOHC engine with variable valve timing (VVT-i). Bore is 81 mm and stroke is 80.8 mm, with a compression ratio of 10.5:1. Official output as per Japanese Manufacturers' Agreement is 206 kW (276 hp) at 5200 rpm although true power output is estimated to be around 230 kW (310 hp). Peak torque of 481 N·m (355 lbf·ft) is at 4000 rpm with over 400 N·m (300 lbf·ft) available from as little as 1200 rpm. The fuel injection system is controlled by two ECUs, one for each bank of cylinders.
The engine is capable of running on a single bank of 6 cylinders should a malfunction occur.
A version is available running on compressed natural gas which produces 190 kW (250 hp) and 420 N·m (310 lbf·ft) and qualifies the 2-ton limousine as a low emissions vehicle. In 2010 the standard engine was revised in order to meet tough fuel economy and emissions standards, reducing power slightly and peak torque to 460 N·m (340 lbf·ft).
One notable use of this engine has been by Top Secret in a custom 950 hp (710 kW) Toyota Supra.