The all-new 2016 Cadillac CT6 is a big, imposing luxury car aimed directly at the BMW 7 Series. GM promises good fuel economy and exceptional handling, thanks to the CT6's light weight. Source: General Motors Company.

General Motors (GM 1.56%) unveiled the all-new 2016 Cadillac CT6 sedan at a posh event in Brooklyn on Tuesday night.

The CT6 is a big, plush luxury sedan built on an all-new rear-wheel-drive architecture. Superficially, it's similar to the top-of-the-line models from the German luxury brands. 

But Cadillac executives at the event went to pains to explain that the CT6 is not a "me-too" product. It was designed -- from scratch -- to offer a distinctly different experience. 

GM hopes the new CT6 will help reestablish Cadillac as a global luxury-car leader -- and indirectly, that its halo will help add billions to GM's bottom line, in time.

Beneath the CT6's skin is a lot of new thinking for GM
The new CT6 really is all-new: It's built on a new rear-wheel-drive architecture, called "Omega," and it was designed from the ground up to serve as a "flagship" (for now -- more on that below) for Cadillac.

It has all of the features you'd expect -- a lavishly trimmed interior with features like massaging seats, a striking exterior, a range of smooth and powerful engines -- and a few you wouldn't: All-wheel steering, for instance, and all-wheel-drive standard in all but the base four-cylinder model. 

The CT6's interior follows recent Cadillac practice, with high-quality hand-sewn leather and well-finished wood trim. Source: General Motors Company.

Yes, there's a four-cylinder version of Cadillac's biggest and most expensive sedan. But it shouldn't be a slouch on the highway: As Cadillac chief Johan de Nysschen explained at length at Tuesday's event, GM has used a mix of lightweight materials -- and some cutting-edge, patented manufacturing techniques -- to produce a big sedan that weighs hundreds of pounds less than its rivals.

GM hasn't released final numbers on the CT6's weight. But GM executives at the event dropped strong hints that its weight would be close to -- if not a bit below -- that of Cadillac's one-size-down CTS sedan. (There were other hints dropped: The CT6 will eventually get a hot twin-turbo V8 engine, as well as a plug-in hybrid version, though neither has been officially announced.)

That light weight will be very impressive if it pans out, as the CTS is a relative lightweight for its size. But light weight is crucial to the CT6's mission: to impress German-brand loyalists as a nimble, fun-to-drive alternative, and project a sophisticated, high-tech halo on the rest of the brand's offerings.

A nimble alternative to the German heavyweights
German luxury powerhouses BMW, Audi, and (to a lesser extent) Mercedes-Benz built their reputations and followings on cars that combined luxurious interiors with engaging levels of power and handling ability. 

They were fun to drive, in other words. And they still are. But Cadillac thinks they've gotten a little soft in recent years -- a little bloated -- and de Nysschen sees a big opportunity there.

It won't happen quickly. Since taking over the Cadillac brand last year, de Nysschen has emphasized that GM fully expects the revival of the brand to take several years. GM is investing $12 billion in this effort, and the CT6 is just the first of eight all-new Cadillacs that GM has promised by the end of the decade.

Still, this is an important effort for GM, because the profit potential is massive. Luxury cars account for only about 10% of the world's auto sales in any given year, but they generate about half of the industry's total profits. GM's bottom line needs that boost.

So, is the CT6 a hit?
I was at the event, I sat in the car and looked it over carefully, and I can tell you that it looks like GM has succeeded in its mission to deliver a credible alternative to cars like BMW's 7-Series. The CT6 looks very good up close, with (in top trim levels, at least) an extremely well-trimmed interior -- and significantly, a roomy and unusually comfortable backseat.

The CT6's backseat has plenty of leg and head room for this 6-foot-tall Fool. GM paid a tremendous amount of attention to the car's rear-seat amenities. Source: General Motors Company.

I say "significantly" because backseats are a critical selling point in China, and GM hopes the CT6 will lead its efforts in the world's largest auto market. GM plans to build it locally, at a new Cadillac-only factory near Shanghai. (CT6s for the U.S. market will be built at a GM factory near Detroit.) 

It's probably not going to set huge sales records, at least initially. GM hasn't announced a price yet, but it'll be expensive -- too expensive for longtime Cadillac loyalists, most likely. And it may be a while before owners of cars like Mercedes' S-Class are willing to take Cadillac seriously as an alternative.

We won't know for sure if the CT6 has hit its target until reviewers have had a chance to test-drive the big Cadillac. Did the all-new platform and promised weight savings really translate into best-in-class handling and a properly luxurious driving experience?

If so, the CT6 will stand a good chance of accomplishing its mission. Stay tuned.