The Nissan NA family of straight-four engines is a series of engines manufactured by Nissan (Nissan Machinery). It is the replacement of the Z series, on which its design is based, and is mostly used in commercial vehicles due to its use of Liquefied petroleum gas for fuel on engines with a "P" suffix code. It is entirely unrelated to the 1950s NAK engine.
In 1998 the NA20P was updated, with redesigned combustion chambers which increased power and torque while lowering fuel consumption. A new catalyst reduced emissions, making it the first LPG-engined passenger car to be designated a low-pollution vehicle in several Japanese cities and prefectures.
This fuel injected, LPG-powered variant was introduced in September 2010 and met new, stricter emissions regulations.