It's hard to imagine a vehicle better suited for cruising the Las Vegas Strip than a Cadillac stretch limousine. It's an excessive car for a town of excess.

Yet even massive, blinged-out luxury limos can go green, to some extent.

MGM Resorts International recently began deploying what it claims is the world's first fleet of natural gas-powered stretch limousines.

MORE: Natural-Gas Vehicles: Honda, Chevy Are 'Neglected Stepchild' Among Green Cars (Sep 2014)

Each vehicle in the 31-car fleet is based on the Cadillac XTS, but is stretched to a full 70 inches longer than the stock sedan.

Running on compressed natural gas (CNG), the limos produce roughly one-ninth the emissions of comparable gasoline models, MGM says.

The natural-gas limos have 200 miles of range, which should be enough for plenty of trips shuttling guests to and from the airport.

2014 Cadillac XTS Limousine

2014 Cadillac XTS Limousine

MGM will likely make its own arrangements for refueling the vehicles at whichever of its properties they will operate from.

There are only a handful of natural-gas fueling stations in the U.S., and most of those are not open to the public.

CHECK OUT: Where Are Natural-Gas Vehicles Most Popular And Most Numerous? (Aug 2014)

Among other factors, that has kept sales of natural-gas passenger cars to decidedly niche levels.

Honda has sold natural-gas versions of its Civic in the U.S. for almost 15 years, moving only about 1,000 to 3,000 units per year.

2014 Cadillac XTS Limousine

2014 Cadillac XTS Limousine

Most of those typically go to fleet operators, who have their own private fueling stations.

Chevrolet also offers a bi-fuel version of its Impala that runs on natural gas or gasoline, and an aftermarket company has offered similar conversion kit for the compact Cruze.

ALSO SEE: 2012 Honda Civic Natural Gas: First Drive (Nov 2011)

Still, remarkably, natural gas probably has a brighter future than the Cadillac XTS itself.

That model is set to be discontinued at the end of its lifecycle--at which point Cadillac is also expected to exit the livery business.

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