The award-winning BMW N54 inline-six has been a hit around the world since it made its debut in the 2006 E90 335i. The twin-turbocharged engine produces around 300 horsepower and 300 pound-feet of torque and many have actually suggested that the Bavarian automaker's power figures have been conservative. When it came out, BMW promised this engine would virtually eliminate turbo lag, increase performance and improve fuel economy at the same time. In fact, it was so confident in its new engine that it spread it around, adding it to its 1, 3 and 5 Series cars, along with its Z4 sports cars and X6 crossovers.

Unfortunately, the N54 has also seen its fair share of owner complaints. Most notably, unhappy BMW drivers allege having two very important issues with the wündermill; the high-pressure fuel pump has a very high failure rate and a defect in the design of the turbochargers requires they be tweaked so as not to run at full capacity. Many BMW owners have officially had it with the N54 engine and a class-action lawsuit has kicked into gear.

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