Car rental companies are trying to cash in on higher gas prices and America’s newfound fascination with all things green. The latest is Advantage Rent A Car, which earlier this week declared its commitment to becoming “the first major all green car rental company in the United States.”

It’s hardly the first — Hertz rolled out a fleet of hybrid vehicles two years ago — and it definitely won’t be the last. But is Advantage really seeing the light when it comes to carbon emissions or just another greenwashing travel company?

A skeptical observer might be forgiven for thinking the latest initiative is nothing more than a fleet upgrade with a clever spin. Here’s what its press release had to say:

Wearing a bright green shirt Tuesday at the American Car Rental Show in Las Vegas, Denny Hecker, Chairman of Advantage Rent A Car, surprised conference attendees by announcing Advantage Rent A Car is committed to become the first major all green car rental company in the United States.

“Our single ownership and nimble fleet size provide us the ability to make a commitment to reduce our carbon footprint in the United States,” says Denny Hecker. “Advantage will offer its customers an environmentally friendly rental alternative, while trying to make a difference in the places where our customers live.”

Advantage has made the commitment to turn 100% of its fleet “green” over the next 24 months subject to manufacturers’ assistance and vehicle availability.

Come on. Hecker “surprised” conference attendees? Coming from a reporter I might buy it.

Coming from a press release, no.

Here’s what’s probably happening. More people want smaller cars that consume less gas. And companies like Advantage and Hertz are just adding more of those vehicles to their rental inventory. That’s what the Arizona Republic reported just before the Memorial Day weekend.

Abraham Rodriquez, manager of Budget Rent A Car’s central reservations center in Los Angeles, said that demand for compact and subcompact cars has increased with gas prices and that many locations quickly run out of those vehicles. As a result Budget is retooling its fleet to include more compact and subcompact cars and fewer gas guzzlers.

Car rental companies are omitting one key piece of information, though. They can — and will — charge us more for these smaller, more fuel efficient rentals if they’re given the opportunity.

So thanks to higher gas prices, car rental companies are seeing green.

After all, that’s the color of money.