Marcus Schneweiss could hardly be heard over the laughter from the crowd.

"This is no laughing matter," he said. "I was driving down the road, and the air conditioning on my new Chevy four-door Malibu didn't work so I told my kids to roll down the back windows."

"They said they couldn't, so I stopped the car to show them how, and what do you know - the windows didn't go down. I thought Chevy had left off the knobs. When I called them, they said they stopped putting roll windows on the back, and that you approved it."

"I had no idea," responded Joan Claybrook, administrator of the National Highway Traffic Safety Administration.

Schneweiss was only one of dozens of speakers at a unique experimental town meeting NHTSA held here Tuesday night. It was an attempt to bring federal regulation to the possible, said Claybrook, who has held six such meetings around the country this year. More than 300 people showed up at a local church to tell the federal regulators everything they ever wanted to know about auto safety problems.

"I came here because I am desperate, this is the last straw," said 21-year-old Donna Robenson, who said that "just about every part on my Volkswagen Rabbit has had to be replaced since I bought it two years ago."

"I was getting nowhere alone," she said, "so I came here because I thought I might get some media attention."

Her ploy apparently worked, as three different reporters waited to talk with her about her problems trying to get Volkswagon to fix what she called her "lemon".

Claybrook recommended Robenson write Volkswagon's president. "I al-get results writing to the top," Claybrook said.

Besides Claybrook, there were representatives of the Federal Trade Commission, the Environmental Protection Agency and several local consumer agencies at the three-hour meeting to help consumers and motorists with their auto safety problems.

After a movie prepared by the Physicians for Auto Safety, and a look at several exhibits and sample safety cars owned by NHTSA, and an air bag demonstration, the crowd settled down for a long night of listening to one consumer gripe after another.

The line of people waiting to use the microphone to address the panel of experts and the audience was dozens of people long virtually all night.

William Randall, owner of a local front-end repair shop, said he had been keeping records of defective radial tires that come in on cars he works on.

"Since Dec. 3, 1976," Randall said, "I have found 522 defective radial tires on my customer's cars - from all manufacturers. I want people to know that this problem is far from over - and does not end with Firestone. Radial tires are dangerous.

Hyman Belber had reason to believe Randall. He reported troubles with four of his five Goodyear radial tires, and felt he had not been properly treated by Goodyear when he complained.

"Just send the serial numbers of the tires to me, care of the Department of Transportation," Claybrook said. tr for add four.

In an emotional gesture, 27-year-old Gregg Sulzen of Maywood, N.J. slowly walked to the microphone with extreme difficulty and a cane because of a serious auto accident nine years ago - caused by a safety defect in a car he owned.

"I was advised to come here by my rehabilitation counselor," Sulzen said, shaking and holding on to his wife Joan for support. "I am an accident victim, and accident was caused by an auto defect."

In an interview after the meeting Sulzen said he was in a comotose state for three months following the accident, in which his steering mechanism locked. He said he suffers from a disease called Hemiparisis.