Twenty years ago, the thought of building a flagship Cadillac sedan without a V8 engine under the hood would have been virtually unthinkable. Nonetheless, in the coming months, the all-new Cadillac CT6 will hit the road to take on the likes of the Mercedes-Benz S-Class and BMW 7 Series with only 4- and 6-cylinder engine options to start with plus diesel and plug-in hybrid electric capability in the future. General Motors (GM) has created what it hopes will be a viable competitor to the segment leaders by harnessing a combination of advanced powertrain technologies and lightweighting to achieve both its performance goals and increasingly stringent fuel efficiency and emissions targets.
Cadillac introduced the first mass-produced V8 engine 101 years ago and, until as recently as 2010, every top of the line Cadillac had a minimum of 8 cylinders under the hood. After first being teased in a television ad run during the 2015 Academy Awards broadcast, the CT6 is debuting at the 2015 New York Auto Show and goes on sale later this year.
Bigger, Better, Not Heavier
In order to help meet the often conflicting goals of performance, driving dynamics, and energy efficiency, Cadillac is incorporating all of the major technologies discussed in Navigant Research’s Automotive Fuel Efficiency Technologies report. Despite its significantly larger size compared to the existing CTS sedan, the CT6 is estimated to weigh about the same 3,600 lbs thanks to extensive use of aluminum in its structure.
A combination of stampings, castings, and extrusions accounts for 64% of the mass of the structure and contributes to an overall reduction of 198 lbs compared to a comparable steel version. GM developed new techniques for laser and spot welding of aluminum in addition to the rivets, screws, and adhesives used extensively by Ford in its new F-150 pickup trucks.
Still High Performance
Starting from a lighter platform enables the engineers to utilize smaller, more efficient engines without sacrificing the performance that customers in this segment expect. At launch, the CT6 will be available with GM’s existing 2.0-liter turbocharged 4-cylinder, an all-new 3.6-liter normally aspirated V6, or a twin-turbocharged 3.0-liter V6 producing 400 horsepower and 400 lbs-ft. of torque. All of the engines feature direct injection and variable valve timing. The V6s will be GM’s first overhead-camshaft engines to feature cylinder deactivation with the ability to disable valve actuation and fuel flow on 2 cylinders under light load conditions.
Each power plant is paired with one of GM’s new 8-speed automatic transmissions and has auto stop-start functionality to shut down the engine when the vehicle comes to a stop to prevent wasting fuel while idling. Cadillac won’t reveal fuel economy numbers for the CT6 until later this year, but the new 3.6-liter V6 is expected to increase fuel economy of the midsize CTS by 9% compared to the 2015 model.
In addition to these advanced gasoline engines, Cadillac plans to add both diesel and plug-in hybrid electric powertrains to its lineup over the next several years. What about the classic V8 configuration? Those are now limited to a pair of niche but still highly profitable segments, the ultra-high-performance CTS-V sedan and the full-size Escalade SUV. The rest of the lineup will rely on fours, sixes, and electrification from now on. It seems that a century after it began, the era of the mainstream Cadillac V8 engine has drawn to a close.
Update: Shortly after this blog was posted, Cadillac president Johan de Nysschen contacted me to confirm that the brand does in fact have a new high-performance V8 engine in development. While V8s will no longer be the volume powertrain, they will remain part of the future Cadillac lineup.