Faulty airbag, hood latch or ignition switch? Who cares?

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That appears to be the attitude of more than 40 percent of American consumers. According to new research from Autotrader, just 56 percent take their vehicle in for repair every time they are notified of a recall.

The findings come on the heels of the largest vehicle recall in U.S. history, affecting more than 34 million car and truck owners.

Citing the recall of more than 80 million vehicles in the past 18 months, Jim Appleton with the New Jersey Coalition of Automotive Retailers suggested consumers have become somewhat "immune" to these notices. They tend to ignore them or put them aside, rather than hurry into the dealership to get the necessary work done.

"There's a certain amount of weariness on the part of the consumer," Appleton said. "They keep getting these recall notices over and over again."

Another part of the problem, he said, is that all recalls fall in the same category, meaning consumers are offered no sense of urgency when the flaw is life-threatening. Appleton is part of a push to develop a "tiered" recall approach nationwide, which would give drivers a better sense of the problem at hand.

"We have literally had recalls for the wrong phone number, the wrong 800 number, in an owner's manual, or a warning sticker that doesn't stick well," he said.

But other recalls connect to major, life or death issues.

The recent widespread recall targets Takata's defective airbags, present in about one-seventh of the vehicles on the road in America. The airbags can violently explode upon deployment and have already caused a number of deaths and injuries.

"The reason something is recalled is for people's safety," said Cathleen Lewis of AAA New Jersey.

She said some consumers believe that if a recall is important enough, they will be bombarded with notifications. But that's not always the case.

"That one letter is going to say you have a recall and you should take it to the shop," she said. "There's not going to be a follow-up. There's no consequences if you don't take it in, other than the fact that obviously your car is unsafe."

According to Appleton, that first notice is a requirement for manufacturers by federal regulators. After that, the dealer at which the vehicle was purchased can choose to send additional notices. Dealers get reimbursed for any recall work performed, so they can profit from the deal.