BMW AG's 3.0L DOHC Turbocharged I-6: Powerful, Efficient, Stimulating

Adding another pair of turbochargers, as well as six cylinders to this year's rankings, BMW AG's 3.0L twin-turbocharged I-6 achieves its third-consecutive spot on the Ward's 10 Best Engines list.

Arguably one of the best volume internal-combustion engines ever produced, the wonderful straight-6 turbo, along with BMW's 10 Best Engines-winning 3.0L clean diesel, support the auto maker's new direction to use advanced compressors and fuel-injection technology to extract the best performance and efficiency from its Ultimate Driving Machines.

The engine serves its purpose well as BMW's answer to its competitors' larger-displacement, normally aspirated V-6s, with the two fast-spooling turbochargers actually helping to produce more low-end torque than the Ford Mustang GT's 4.6L V-8 of similar power.

And because of direct-gasoline injection and relatively low boost pressures, there virtually is no noticeable lag in power delivery, just immediate surges of thrust.

Hardly any negative comments made it on to the judges' evaluation sheets this year, with a few minor protests noting observed fuel economy could have been better.

This engine is extremely capable, whether in a sports car or in a cross/utility vehicle, and advanced enough to remain relevant for years.

Engine type: 3.0L twin-turbocharged DOHC I-6

Displacement (cc): 2,979

Block/head material: aluminum/aluminum

Bore × stroke (mm): 84 × 89

Horsepower (SAE net): 300 @ 5,800 rpm

Torque: 300 lb.-ft. (407 Nm) @ 1,400-5,000 rpm

Specific output: 100 hp/L

Compression ratio: 10.2:1

Assembly site: Steyr, Austria

Application tested: 135i coupe

EPA city/highway (mpg): 17/25