The 2016 Cadillac CT6 will be a new top-of-the-line luxury sedan. Its styling is expected to draw heavily from that of last year's Cadillac Elmiraj show car. Source: General Motors Company.

Yes, the brand's U.S. sales are down this year. Yes, it's still lacking strong products in some of the industry's most important segments.

But it may soon be time to start taking Cadillac very seriously.

General Motors' (GM -0.47%) global product chief Mark Reuss shared some details on several upcoming new Cadillacs on Wednesday, including the all-new CT6 super-sedan that is set to debut next year.

And one thing is becoming very clear: GM is not messing around anymore.

More details emerge on GM's Cadillac of Cadillacs
GM on Wednesday held an all-day briefing for select Wall Street analysts at its testing facility in Michigan. Media members were not invited, but we were able to listen to the presentations by phone -- and we got copies of some of the presentation slides.

During his presentation, Reuss showed a preproduction version of the 2016 Cadillac CT6 to the group. I couldn't see it myself, of course, but I could listen to Reuss as he listed some of its innovative features. 

The CT6 is a new Cadillac sedan that will slot in above the CTS and XTS in Cadillac's current model range. It is expected to be bigger than those cars -- eight inches longer than a CTS, Reuss said on Wednesday. 

It'll also be lighter than the already-light CTS: 25 kilograms lighter, Reuss said, thanks to a special welding technique -- patented by GM -- that allows the body to be constructed from an innovative mix of aluminum and high-strength steel parts. It should also be much stiffer, he said, which should improve the car's ride and handling -- while making it quieter inside.

This slide from Reuss' presentation hints at the CT6's shape. Source: General Motors Company.

GM has promised a host of new high-tech features for the CT6, which Reuss described at "the most technologically advanced vehicle in the world." Those features are expected to include the first production version of GM's "Super Cruise" self-driving system. And Reuss confirmed what your humble Fool recently guessed: There will be a plug-in hybrid version of the CT6.

That's all promising. Technology has become a major selling point in the luxury-car market, and GM is clearly aiming to trump the German brands' latest advances.

But will the CT6 really be able to take on the top-of-the-line cars from Daimler's (MBGA.F 0.32%) Mercedes-Benz and the other German luxury makers?

Recent Cadillacs have been very good
It seems likely that the CT6 will be able to stand comparison with Germany's best sedans. After all, the new-for-2014 Cadillac CTS has won a host of awards, including Motor Trend's Car of the Year award, and has shined in comparison tests against the BMW (BAMXF -0.19%) 5 Series and the Mercedes-Benz E-Class.

But Cadillac may not position the CT6 as a direct rival to the S-Class and BMW's 7 Series. As reported by the Daily Kanban, new Cadillac president Johan de Nysschen recently said, "CT6 is not positioned against S-Class, 7 Series or [Audi] A8. It will have more advanced technology, better dynamics, similar refinement but it is smaller."

The CT6 will be the first GM car to include its new "Thru View" rearview mirror, which uses the car's backup camera to present an unobstructed view to the driver, Reuss said on Wednesday. Source: General Motors Company.

De Nysschen also hinted that the CT6 may not be Cadillac's long-term "flagship." There have been hints for a while that GM may have an even larger, more expensive Cadillac sedan in the works.

But Cadillac's recent track record suggests that the new CT6 should be very good. 

Why the CT6 needs to be very, very good
Much has been made of Cadillac's sluggish U.S. sales this year. After a strong 2013, the brand has struggled, with sales down 1.3% through September.

But from a global perspective, Cadillac isn't doing as badly as that number would suggest. Cadillac spokesman David Caldwell told me last month that the brand's global sales were up 10% this year through August, thanks to big gains in China. 

The new-for-2014 Cadillac CTS impressed critics. The CT6 will need to be at least as impressive. Source: General Motors Company.

And even here in the U.S., Caldwell said, Cadillac's average transaction price has been over $49,000, higher than those of the German luxury brands.

But there are still big holes in Cadillac's product lineup. The brand urgently needs a compact crossover (or two) to rival vehicles like BMW's hot-selling X3 and Mercedes' new GLA. A rear-wheel-drive Cadillac car one size smaller than the ATS sedan -- along the lines of BMW's 1 Series or the Audi A3 -- would also help. 

Those vehicles are coming, de Nysschen says. But before they arrive, Cadillac will launch the CT6, positioning it -- for now, at least -- as its top-of-the-line product. Its debut will coincide with the beginning of a major new marketing campaign for the Cadillac brand, as de Nysschen and Cadillac marketing chief Uwe Ellinghaus begin a major effort to raise Cadillac's prestige.

For that effort to succeed, the CT6 will need to be really good. Will it be? We'll find out soon.