The agency that runs Tampa International Airport might begin charging a $2.50 fee on every car rental contract issued there, according to the St. Petersburg Times.

Faced with a car rental facility operating close to full capacity, the Hillsborough County Aviation Authority will consider the new fee to use $8.9 million annually for expansion and to pay down debt for current rental facilities.

The four on-airport car rental tenants that pay about $30 million a year in rent informally agreed to the fee, which will fund a $20 million, two-year overhaul of the main terminal building.

Most of the first phase will be completed before the Republican National Convention in Tampa next summer. The phase includes $1.5 million for 11 billboard-sized digital TV screens showing videos in the baggage areas and upgrading the restrooms.

Tampa is one of the few airports in the United States with a covered car rental ready line so close to the baggage areas. But since National/Alamo moved to the terminal, the capacity of 1,300 cars there has been pressed.

Less than 5 percent of car rental deals are booked by local residents. Tampa is among the few big airports not charging a fee.

Airport chief executive Joe Lopano's proposed $175.5 million budget for the fiscal year that begins in October assumes passenger traffic will increase 2 percent to more than 17 million passengers next year.

The budget envisions spending $263,000 to convert the bus fleet to natural gas, $4.8 million to replace air-conditioning towers so they run on reclaimed water and $152,000 to equip the airport's fleet of eight police cars with videocameras.