The limousine that burst into flames on the San Mateo Bridge, killing five women, wasn't required to undergo a state safety inspection -- or even carry a fire-extinguisher -- under the regulations that are supposed to ensure the thousands of limos on California's roads are safe.

Like most stretch limos, the 1999 Lincoln Town Car had been modified -- cut in half, its fuel and electrical lines severed and rebuilt with a large passenger compartment in the middle. But since the car was licensed to carry fewer than 10 people, the state doesn't require routine safety inspections. Such inspections are required every 13 months for larger limos, airport shuttles and buses.

San Mateo County firefighters and California Highway Patrol investigate the scene of a limousine fire on the westbound side of the San Mateo-Hayward bridge
San Mateo County firefighters and California Highway Patrol investigate the scene of a limousine fire on the westbound side of the San Mateo-Hayward bridge in Foster City on May 4, 2013. Five women died when they were trapped in the limo that caught fire as they were traveling. Four women and the driver were able to escape. (Jane Tyska/Staff file)

The inspection loophole -- and the lack of fire extinguisher requirements -- raised new concerns Tuesday as authorities continued what they say will be a lengthy investigation into what caused Saturday's horrific inferno. And it provided little comfort during the heart of the spring prom and graduation season to people asking just how safe are California's limos.

Tuesday, state Sen. Jerry Hill, D-San Mateo, said he would introduce a bill next week requiring fire extinguishers in limos and would also explore why the cars carrying 10 or fewer people, including the driver, are not inspected.

"Once that vehicle is modified, the bigger ones have the same structural changes as the smaller ones," said Hill, whose district includes the San Mateo County side of the San Mateo-Hayward Bridge. "Everything is identical. That makes no sense."

Experts say radical modifications to lengthen cars can add stress to key systems like fuel lines and electrical wiring.

But the state agency that regulates and licenses limos, the Public Utilities Commission, has no rules or standards about how stretch limousines are built from standard cars, its spokeswoman, Terrie Prosper said Tuesday.

The 28-foot limousine that burst into flames Saturday was owned by Limo Stop Inc. of San Jose and San Francisco, which had no record of consumer complaints since it opened in 2006. In interviews Monday, the driver, Orville "Ricky" Brown speculated that an electrical problem may have sparked the blaze, because he didn't smell gas when the group celebrating a friend's recent wedding started screaming about smoke rising from the passenger compartment floor. The car was carrying nine passengers -- one more than it was licensed for -- but officials haven't said if that was a factor.

Statistics about limousine fires and deaths are difficult to come by -- partly because they are rare -- and the state can't even say how many converted stretch limos are on California's roads.

There are 6,600 companies in the state licensed to operate limousines, Prosper wrote in an email Tuesday, but some of them are bus and van companies that may not operate limos. She could not say how many limos there are and the Department of Motor Vehicles does not track them. The Maryland-based Taxicab, Limousine & Paratransit Association estimates there are about 45,000 stretch limos in the country.

"You're dealing with a very under-regulated industry,'' said Clarence Ditlow, executive director of the Center for Auto Safety, a group founded by Ralph Nader. Ditlow said drawing the line at inspecting only vehicles that carry at least 10 people "is just an arbitrary line. You can have a tragedy, as you did in San Mateo, in a vehicle that escapes regulation."

The process known as "stretching," which greatly lengthens the car's wheel base, creates "stresses and vibrations" on systems that can create damage over time, auto safety experts say.

"The government doesn't appear to be concerned with the modification of the vehicle, just the number of passengers," said Keith Friedman, an auto safety expert and accident investigator from Santa Barbara. "You need to take that into account. Most of the people doing the work aren't engineers."

Custom car builders strip the interior, cut the car in half and insert a steel frame, panels and windows up to the desired length. Part of the process is unhooking electrical cables and fuel lines and then reattaching them in the new, longer car, said Phil Restivo, owner of Santa Clara-based LeGrande Affaire Worldwide Ground Transportation. He said his company conducts safety inspections on its limos before every trip."There's a lot of manufacturers out there that will try to save a buck (or) two, here or there, and they don't look at the longevity of the vehicle," Restivo said. "We pay close attention to the small things."

The fire, and revelations about lack of oversight, are scary, said Jenny Brandt, a lawyer who lives in San Leandro and is planning a friend's bachelorette party later this month that includes a stretch-limo ride to Napa wineries.

"I had no idea that limos were modified from town cars," she wrote in an email Tuesday. "I just figured they were built that size."

Now she wants to know when the limo she reserved for nine people was last inspected.

The editor of a limousine industry trade journal said some vehicles like Lincolns and Cadillacs are modified into limos based on manufactures' recommendations while others are not. Lincoln Town Cars -- the kind that burned Saturday -- are extremely popular for conversions to limos, said Martin Romjue, editor of Limousine, Charter & Tour Magazine, which is based in Los Angeles.

"They are a high quality work horse, the standard vehicle of the industry," Romjue said. "I have never heard of anything like (the fire) before. A lot of people in the industry are saying this is (the) worst (limo) accident they've seen."

Romjue said consumers should use common sense when picking a limo company, starting with making sure it is licensed by the PUC.

"Go take a look at the vehicle" before renting it, he said. "Ask the company about safety and (driver) training."

He also said that passengers should agree among themselves to never pile more people into a car than is permitted and walk away from unscrupulous drivers who offer to carry more.

"It is clearly an industry standard to never exceed the passenger limit."

Reach Thomas Peele at Tpeele@bayareanewsgroup.com; follow him at twitter.com/Thomas_peele. Reach Joshua Melvin at Jmelvin@dailynewsgroup.com; follow him Twitter.com/ melvinreport.

HOW TO CHECK OUT YOUR LIMO COMPANY

Make sure the company is licensed by the state Public Utilities Commission.
Take a trip to the limo company and ask to see the car you will be renting.
Be certain the charter-party carrier (TCP) permit number is displayed on the limousine.
Verify that the TCP permit number is accurate by checking with the CPUC.
Ask the company about safety and driver training.
Never pile more people into a car than is permitted, and walk away from unscrupulous drivers who offer to carry more.
For more information, go to: http://docs.cpuc.ca.gov/PUBLISHED/NEWS_RELEASE/100776.htm.