Rental-car taxes can be used to fund sports stadiums or projects to promote tourism and industry.

But a new bill proposed by a Republican state lawmaker from Savannah would expand the use of those proceeds to pay for existing or new public transit projects.

The idea is not a new one, but it does have a twist. It specifically excludes counties that “levy a tax dedicated to public transportation, including, but not limited to, a tax levied under the provisions of the Metropolitan Atlanta Rapid Transit Authority Act of 1965.”

That means if the legislation passed, DeKalb and Fulton counties would be ineligible to use rental-car tax revenue for funding MARTA or the Atlanta Streetcar.

Rep. Ron Stephens, who introduced House Bill 765 on Thursday, said it was aimed at helping "a Chatham County (transit) system," but did not offer further details.

“It’s to get a conversation started,” said Stephens, who chairs the House Economic Development and Tourism Committee.

Sen. Vincent Fort, an Atlanta Democrat, introduced a similar bill last year, Senate Bill 92, but Fort's bill would have allowed the rental-car tax to be used for mass transit anywhere in the state.

The bill made it over to the House, but the session ended before it came to a final vote. Fort said he intends to talk to Stephens and see if they can work together on the issue, adding “whatever gets the job done is what I’m concerned about.”

Whatever happens, Fort intends for the bill to help Fulton and DeKalb counties, and MARTA in particular.

“I just think the exclusion of Fulton and DeKalb is not a good thing,” Fort said.

It’s unclear whether metro Atlanta counties would even want to tap rental-car taxes as a potential funding source for transit, or how much transit could benefit from such a tax.

A 3 percent citywide rental-car tax in Atlanta could potentially bring in $4.5 million a year, according to a 2013 study on the proposed Multi-Modal Passenger Terminal for downtown Atlanta.

A 3 percent tax on car rentals in unincorporated Cobb County is projected to bring in $400,000 a year for debt service on the new Braves stadium, if commissioners approve the plan later this year.

However, those amounts pale in comparison to the $7.2 billion that would have been raised from a 10-year, penny sales tax (commonly known as T-SPLOST) that metro Atlanta voters rejected in July 2012. It also would make barely a dent in MARTA’s $427 million operating budget or its $430.5 million capital budget.

A heavy rail expansion of MARTA, such as one planned along I-20 East from central Atlanta to Panola Road (although not currently scheduled to be built until after 2031), could easily exceed $1 billion.