Anyone who has searched for parking in San Francisco and noticed space after space taken by cars with blue disabled placards dangling from their rearview mirrors might wonder whether the city could possibly have so many drivers with disabilities.

Probably not, say transportation officials, advocates for people with disabilities, the state auditor and a Bay Area legislator. They say it’s time to do something about the fraudulent use of disabled placards.

“Way too many are inappropriately used either by a person using a relative’s placard or a dead person’s or one they obtained at a flea market,” said Bob Planthold, a San Francisco advocate for the disabled. “There are too many people using them for their own convenience.”

The plastic placards grant those who have them the privilege of parking free for as long as they want, not only in blue disabled spaces but also at parking meters and in green zones.

The promise of free, convenient, unlimited parking makes cheating a temptation, said Jaime Garza, a spokesman for the state Department of Motor Vehicles, and has fueled a surge in the number of fraudulently obtained or illegally used permits.

A state audit released in April found that most placard applications lacked proper descriptions of the recipients’ disabilities. It also found that tens of thousands are held by people who are dead or over 100 years old.

According to the audit, 35,000 disabled-placard holders were listed as deceased in the Social Security Administration’s records and another 26,000 placard holders were 100 or older. California is believed to have just 8,000 centenarians. The state does not require families to return the placards or notify the DMV when an authorized user dies.

“There are people who will keep using a dead relative’s placard,” Planthold said, “and they’ll ... keep getting (new) placards in the mail. Some people, when a relative dies, will go to a flea market and sell the placard and get several hundred bucks for it.” Permanent disabled placards expire every two years and are automatically renewed.

In San Francisco, where parking anywhere is hard to find, there are 700 blue-painted disabled parking zones and 29,000 metered parking spaces. A total of 65,000 city residents have been issued disabled parking placards. In all of the Bay Area, more than 500,000 people hold placards.

Concern that people with unauthorized permits are stealing parking from people with disabilities and depleting the city’s already insufficient supply of street parking has led to calls for a crackdown beyond increased enforcement.

Some are urging changes in the way disabled parking placards are issued, distributed and monitored, and a group in San Francisco has raised the idea of eliminating the free-parking part of the permit.

“We’re not trying to just get parking for us,” Planthold said. “But parking for you who are not disabled can also be a problem.”

The DMV, which oversees the Disabled Person Parking Placard Program, stepped up enforcement stings and publicized them after the state audit came out.

In June, DMV investigators carried out 22 sting operations, resulting in 195 citations out of 1,633 drivers selected randomly for questioning. Citations can cost anywhere from $250 to $1,000.

Choosing locations based on complaints, investigators questioned drivers who pulled into spaces in cars displaying placards. They asked to see the placards, which contain an identification number, as well as ID to determine whether the holder was authorized to have the blue card. Placards are issued to individuals, not cars.

The number of citations issued during the department’s June stings indicated that about 1 in 8 placards was being used fraudulently.

“One out of every 20 or 30 is good,” said Jaime Garza, a DMV spokesman, “but some of them are 1 in 8. It varies by time of day, day of the week and location.”

San Francisco’s Municipal Transportation Agency, which confiscates about 1,500 placards a year that are fraudulently used or obtained, has its own parking force overseeing disability parking, along with regular parking enforcement officers.

“Enforcement is an important part of finding a solution to more parking for people who need it,” said Paul Rose, an MTA spokesman. “But it’s not the only way to provide better access for disabled people.”

Four years ago, a committee convened by the Mayor’s Office on Disability recommended increasing enforcement and upgrading oversight of how placards are issued and who certifies someone as eligible.

It also recommended setting parking time limits for people with disabled placards and requiring them to pay at meters like other drivers. But enacting those proposals would require changes in state law, and efforts in Sacramento went nowhere.

However, some lawmakers did show interest this year following the stinging report by the state auditor, which concluded that the DMV “does not sufficiently ensure that applications for placards are legitimate.”

The auditor recommended the DMV and Legislature conduct quarterly audits of applications, determine whether some people are getting an excessive number of replacement placards, and check Social Security lists to cull dead people’s names from the placard rolls.

The recommendations also call on the DMV to develop technology that will make it easier for city parking control officers to check the validity of a placard. DMV Director Jean Shiomoto agreed to implement all 16 recommendations in the audit.

Legislation proposed by state Sen. Jerry Hill, D-San Mateo, would require the DMV to conduct quarterly audits of applications, in conjunction with state health boards. It would also make placard holders apply for renewals every four years and limit the number of replacement placards to two every two years.

“If you have a placard fraudulently, you know you’re not going to get caught,” Hill said. “We need to change that.”

Michael Cabanatuan is a San Francisco Chronicle staff writer. Email: mcabanatuan@sfchronicle.com Twitter:@ctuan