General Motors unveiled the Cadillac Escala Concept in California on Thursday. The Escala Concept is a preview of the brand's upcoming styling changes. Image source: General Motors.

General Motors (GM -0.47%) unveiled a show car on Thursday that it says is a preview of a styling overhaul coming to its Cadillac luxury brand. It's significant for what it says about GM's plans for Cadillac -- and that's not all good news.

The Cadillac Escala: A styling preview that might go into production

GM unveiled the Cadillac Escala Concept at a private event near the Pebble Beach Concours d'Elegance in California on Thursday night. In recent years, Cadillac has used the important Pebble Beach classic-car show as a forum to display futuristic concepts like 2011's Ciel and the Elmiraj in 2013. 

The Ciel and Elmiraj were strictly "concepts," show cars intended to preview the future direction of the Cadillac brand. The Escala is that too, but Cadillac's president, Johan de Nysschen, said that it could go into production in a few years if there's demand. 

So what is it? The Escala is a big luxury sedan with a split personality. It's a powerful car that should have great handling -- but at the same time, a lot of attention was paid to making the backseat a luxurious place where adult-sized people can stretch out a bit. (By the way, Cadillac made a point of explaining that "escala" is Spanish for "scale," apparently a nod to the car's size.) 

Image source: Cadillac.

Up front, the Escala sports three curved OLED screens that are layered in front of the driver, along with a central control module that allows for voice, gesture, or tactile commands for control and connectivity features. It's a prototype of a system coming to production on Cadillacs, the company said. 

In back, a pair of deep-set seats allow for plenty of legroom, while three touchscreen displays provide infotainment and controls to the rear-seat passengers. It's all swathed in leather and walnut in shapes that hint at Cadillac's heritage while being very modern. There's also something different, at least by modern luxury-car standards: cloth fabric "inspired by suiting material used by Cadillac's partners in the fashion industry."

There are touchscreens hidden in the two front-seat backs and in the center armrest. Image source: Cadillac.

The emphasis on rear-seat comfort may seem like overkill to Americans, but remember that Cadillac is a fast-growing brand in China, where many luxury-car owners hire drivers to deal with the crazy traffic in cities like Beijing and Shanghai. 

"My brief to the designers was to create a car you desperately want to drive, and also one in which you want to be driven," Cadillac's design chief, Andrew Smith, said. "So rather than a single design, this interior consists of two themes." 

For the most part, the Cadillac Escala Concept is a terrific design full of good high-tech touches. But it's missing something big, something that we've recently come to expect in cars that offer a preview of the future of luxury brands. 

What Cadillac left out of the Escala Concept is significant

Where's the electric drivetrain?

Cadillac's German rivals are very aware of the success of Tesla Motors (TSLA -1.06%), and they're all gearing up to compete. The talk at Mercedes-Benz and BMW and Audi these days is all about electric drivetrains. All three have big electric sedans and SUVs in development. (In fact, Mercedes showed off a very upscale electric concept car at its own Pebble Beach event on Thursday.)

So where is Cadillac's electric luxury sedan? Why wasn't this it?

At minimum, I expected the Escala to feature a more powerful version of GM's excellent plug-in hybrid system, the new one developed for the latest Chevrolet Volt. If nothing else, it would be helpful to have in China, where several cities are restricting access by vehicles that don't have zero-emissions drivetrains. But no: The Escala is powered by a 4.2-liter twin-turbo V8.

The rear of the Escala Concept carries forward Cadillac's long-standing "vertical lighting" styling theme. But unlike other Cadillac sedans, this one has a liftback rather than a traditional trunk. Image source: General Motors. 

Now, there's nothing necessarily wrong with that. That 4.2-liter V8 has been in development for a while, and it's likely to go into production soon. From conversations I had with some GM executives last year, I expect it to show up as an option on the current CT6 sedan, and possibly in the midsize CTS as well. It's a powerful, advanced, fuel-efficient engine that is mechanically related to GM's very well-regarded 3.6-liter V6.

If GM builds the Escala, that 4.2-liter V8 should make it a lot of fun to drive. But if you're showing off the future of a luxury-car brand in 2016, shouldn't it be electric?

This feels like a missed opportunity for GM

Cadillac has recently become somewhat more independent of the General Motors hierarchy, but it's still part of GM. GM is the company that is about to beat Tesla Motors to market with an affordable 200-mile electric car. It's the company that has recently leapfrogged to the forefront of self-driving research. 

De Nysschen's boss, CEO Mary Barra, talks frequently and convincingly about "disrupting" GM before Silicon Valley does. Electric cars are a big part of that, but so far GM's visible efforts have been focused on the affordable end of the market, where electric cars are still a tough sell. But Tesla has shown us that stylish, well-executed electric luxury vehicles can post strong sales.

An ambitious push into high-performance electric drivetrains seems like a natural fit for the direction de Nysschen wants to take the Cadillac brand and where Mary Barra is taking GM as a whole. So why is Cadillac sticking with gasoline? As impressive as it is, the Escala feels like a missed opportunity to showcase a step forward for Cadillac, one that makes this GM shareholder wonder what they were thinking.