2023 BMW K1600 GT Motorcycle: Straight-Six Fix

From the December 2023 issue of Car and Driver.

Certain machines are intrinsically linked to specific power sources. Chevrolet Corvettes and small-block V-8s. Ram heavy-duty trucks and Cummins diesels. Joey Chestnut and Nathan’s Famous hot dogs. BMW is among this cohort too. For decades, the company was synonymous with the naturally aspirated inline-six, an engine configuration that in the 1980s became the smooth, pulsing heart of the German automaker’s lineup.

As time went on, BMW’s velvety, rev-happy straight-sixes evolved into turbocharged engines that had far more horsepower but lacked the character of their naturally aspirated predecessors. BMW still builds an inline-six that forgoes forced induction. However, it only bolts this engine to a motorcycle.

The 1.6-liter unit attached to the BMW K1600 has many hallmarks of the naturally aspirated sixes that powered the company’s cars, including double overhead cams that operate four valves per cylinder and effortless power all the way up to the 8500-rpm redline.

BMW mounts this 160-hp straight-six transversely within the motorcycle’s narrow frame, laying it forward at a 55-degree angle, almost as if it’s the foundation of a rear-facing chaise longue. The crankshaft output isn’t at either end of the engine; rather it’s a toothed gear placed between the second- and third-cylinder throws. BMW mounts the bike’s six-speed sequential transmission transversely too, and its output drives the rear wheel by way of a shaft.

We don’t sample nearly as many motorcycles as we do cars in a year, and yet the K1600 feels extra special. It has electric reverse, anti-lock brakes, traction control, heated seats and grips, a power windscreen to keep rider and passenger out of the heavy air, and an adaptive LED headlamp. It also offers a stereo, but we are staunch opponents of such tomfoolery. If you insist on listening to music on a motorcycle, stick with a Bluetooth link to helmet-mounted headphones. Everyone in traffic around you will appreciate you. Besides, getting on a motorcycle is about unplugging.

Inline-six engines produce silky sounds and provide perfect primary and secondary balance. This inherent smoothness translates to a buttery motorcycle built to tally many miles over many days in the saddle—with no V-twin posterior massage. The transmission also features what amounts to no-lift shifting. Once you get rolling, you no longer need to use the clutch to change gears. You get used to the lack of left-finger work quickly, as the system operates very smoothly.

The K1600 is a line of motorcycles and the GT model we borrowed is the sportiest of the bunch. Others offer a more comfortable passenger seat with more storage, or a more relaxed cruising position complete with forward foot pegs. About our only ergonomic complaint with the GT is the saddle bags, which remove from the bike and can be locked and unlocked with the keyless fob, but they aren’t big enough to store a helmet (at least not an Arai Contour X) or carry a bag with a full-size laptop. Both examples are very close to fitting.

A big engine means a big bike, and the powertrain alone accounts for 226 pounds of the K1600 GT’s 782-pound curb weight. Even when dwarfed by stopped four-wheeled traffic, the 7.6-foot-long Beemer feels enormous. Only when underway does it shrink around you just as great-handling big cars do. As ridden, with most of the bells and whistles, the GT costs less than $30,000, and if we were given our choice of brand-new $30K vehicle for making a transcontinental trip, the K1600 GT would be right up there with any car in that range. But more important, just one twist of the K1600 GT’s throttle was all it took to convince us that BMW needs to bring the naturally aspirated inline-six back to its lineup, even if it is in just one very special M car. Please.

K.C. Colwell is Car and Driver’s executive editor, who covers new cars and technology with a keen eye for automotive nonsense and with what he considers to be great car sense, which is a humblebrag. On his first day at C/D in 2004, he was given the keys to a Porsche 911 by someone who didn’t even know if he had a driver’s license. He also is one of the drivers who set fast laps at C/D‘s annual Lightning Lap track test.