The n46 is a 2.0-litre four-cylinder naturally aspirated engine developed by BMW itself, and is carried on the fifth generation of the BMW 3 Series, codenamed E90. As of September 2019, the b46 has been completely discontinued in favor of the n20 four-cylinder turbo engine and the b48 six-cylinder turbo engine. The n46 engine has a maximum horsepower of 152 HP, a maximum power of 112kw and a maximum torque of 200N·m. As a naturally aspirated engine, the n46 is more powerful in its class and, at the same time, has better fuel economy. n46 is mainly carried in BMW's pre-2012 models, as of 2019, most of BMW's models have adopted turbocharged engines, and naturally aspirated engines have slowly withdrawn from the historical stage. Compared to naturally aspirated engines, turbocharged engines are more powerful, and the power of a 1.4-litre turbocharged engine is basically equivalent to that of a 2.0-litre naturally aspirated engine. What's more, turbocharged engines have better fuel economy and are more fuel efficient.