The QG engine is a 1.3 L, 1.5 L, 1.6 L, and 1.8 L straight-4

Straight-4

The inline-four engine or straight-four engine is an internal combustion engine with all four cylinders mounted in a straight line, or plane along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft....

 piston engine from Nissan. It is a lean-burn aluminum DOHC 4-valve design with variable valve timing

Variable valve timing

In internal combustion engines, variable valve timing , also known as Variable valve actuation , is a generalized term used to describe any mechanism or method that can alter the shape or timing of a valve lift event within an internal combustion engine...

 and optional NEO Di direct injection.

The QG engines were designed for Nissan by Aichi Machine Industry, Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

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Nissan websites state the QG as standing for "Quality and Green".
The QG13DE is an 1.3 L (1295 cc) DOHC 16-valve with 4-cylinder.