The ZR engine is a family of straight-four 16-valve all-aluminum and water cooled gasoline engines with a die-cast aluminum block and variable valve timing developed by Toyota Motor Corporation, produced from 2007. Engines displace from 1.6 to 2.0 liters. Most engines in this family are equipped with Toyota's dual VVT-i technology that optimizes both intake and exhaust valve timing. This engine family is also the first to use Toyota's Valvematic system, first appearing on the Noah and Voxy in 2007 and then the European Avensis in 2009.

VVT-i, or Variable Valve Timing with intelligence, is an automobile variable valve timing technology developed by Toyota. It was introduced in 1995 with the 2JZ-GE engine found in the JZS155 Toyota Crown and Crown Majesta.