Among car buyers, none of the four surviving General Motors brands are really associated with hybrid vehicles.

Now that customer deliveries have started for the 2011 Chevrolet Volt extended-range electric car, GM's other brands will need some green cred too.

What's the future of GM's Two-Mode Hybrid system for medium and large vehicles?

Who gets hybrids?

And if Chevy now has the Volt, which GM brand becomes the lead for regular and plug-in hybrids?

We think it'll be Cadillac. Here's why.

2012 Buick LaCrosse eAssist Live Shots

2012 Buick LaCrosse eAssist Live Shots

Buick Lacrosse Hybrid eAssist System

Buick Lacrosse Hybrid eAssist System

Buick: no H-word

Buick has no hybrids at all. Instead, for 2012, it will offer its LaCrosse midsize sedan with what it calls the eAssist system--a start-stop function that's really a mild hybrid, though the H-word never crosses the marketer's lips.

Which is probably a good thing, since buyers who think of a "hybrid" car probably expect it to have at least some ability to run on pure electric power at low speeds. And GM's second-generation mild-hybrid system (now named eAssist) may not offer enough of that to make an impression.

What about GMC?

That takes care of Chevy and Buick. GMC is a truck brand, and sales of GM's hybrid pickups have been nothing short of dismal, as pickup truck buyers are less likely to buy a hybrid to show their green credentials. They will only pay the extra cost if they get the money back in gas savings--which, at $3 gasoline, they don't.

2009 Cadillac Escalade Hybrid Platinum

2009 Cadillac Escalade Hybrid Platinum

That leaves Cadillac. Right now, it has the hulking 2011 Escalade Hybrid, its surprisingly fuel-efficient version of GM's full-size V-8 sport utility vehicle. The big 'Slade has two plainer siblings, the 2011 Chevy Tahoe Hybrid and 2011 GMC Yukon Hybrid.

Four reasons

Here are the four reasons we think Cadillac will take the lead within GM on hybrids.

First, the Escalade Hybrid sells better (as a proportion of overall model sales) than either the hybrid Tahoe or Yukon. Upscale Cadillac buyers are more willing to pay the money for a technology that lets them say "hybrid," even if it doesn't pay back.

If you can spend an extra $30K-plus for fancier trim and a Cadillac badge, a Hybrid option--complete with flashy fist-sized chrome "Hybrid" badges in either front fender--is just another luxury option to tick.

Cadillac XTS Platinum Concept

Cadillac XTS Platinum Concept

Second, at last January's 2010 Detroit Auto Show, Cadillac showed a stunning XTS Platinum concept car that included a plug-in version of the Two-Mode Hybrid system.

The XTS concept foreshadows the replacement for the current Cadillac DTS sedan late in 2012, so this is a thinly-veiled hint of things to come.

First plug-in: a crossover

Third, at that same show, former GM product czar Bob Lutz told reporters that GM's first plug-in hybrid wouldn't be the XTS sedan but a smaller crossover. Indeed, the plug-in hybrid powertrain was originally meant for the stillborn Saturn Vue small crossover.

2010 Cadillac SRX Turbo

2010 Cadillac SRX Turbo

After deciding to euthanize Saturn, GM planned to re-badge the Saturn Vue as a Buick, but that idea was quickly axed. Initial expectations switched to the crossover plug-in landing in either the Chevrolet Equinox or GMC Terrain.

But lately, rumors point instead to the Cadillac SRX, its well-received new small crossover.

Benz will have one too

Finally, Cadillac is forging ahead with its quest to be considered in the same class as German luxury performance cars like Mercedes-Benz and BMW. Benz, for one, will launch an S500 Plug-In Hybrid version of its next S-Class large sedan in 2012.

2009 Mercedes-Benz Vision S500 Plug-In Hybrid Concept

2009 Mercedes-Benz Vision S500 Plug-In Hybrid Concept

Lutz said as far back as late 2008 that Cadillac could get its own plug-in hybrid.

That may have referred to the Cadillac Converj electric coupe shown in Detroit in 2009, which used the Voltec powertrain from the Chevy Volt. In the end, the Converj was not approved for production for financial and other reasons.

What's ahead?

The plug-in hybrid system in the XTS Platinum pairs a 3.6-liter, 350-horsepower direct-injection V-6 engine with the Two-Mode Hybrid transmission and an 8-kilowatt-hour lithium-ion battery pack that recharges on wall current in about five hours.

So here's our prediction: For 2012, we'll see an SRX Plug-In Hybrid.

For 2014, one year after the launch of the 2013 Cadillac XTS in standard V-6 format, we'll see an XTS Plug-In Hybrid as well.

What do you think? Is Cadillac the right place for hybrids? Leave us your thoughts in the Comments section below.