Like the predecessor, the 2AR engine has aluminum cylinder block with thin cast iron liners inside. The block cannot be repaired for this engine. Liners are not replaceable. Inside the block, there is forged steel crankshaft moved by 10 mm to the exhaust side (an offset crankshaft). The crankshaft has eight counterweights and is fully balanced. The crankshaft drives two balancer shafts through a gear inside the crankcase kill vibrations. The significant changes are in the cylinder head. The head is DOHC 16-valve and made of aluminum alloy. It has hydraulic lifters (the 2AZ has not). There are two camshafts, and each of them is equipped with a variable valve timing system called Dual-VVTi. There are roller rockers for the valvetrain. The engine was developed by applying low friction technologies. The pistons use reduced-tension piston rings. The oil pump is variable and has three-stage of operation.
The 2AR-FE was released in 2008. It came to replace the 2.4-liter 2AZ engine. The engine consumes less fuel than the predecessor, but the output is on the same level. Engineers achieved such result by applying modern technologies in the engine development. Together with the 2.5-liter engine, the manufacturer also produces the 2.7-liter engine 1AR-FE.