While big technological hurdles remain, the potential rewards of self-driving cars are enormous, both for society and the car industry. Such vehicles would allow drivers to be productive at times when they are otherwise stuck in traffic. They could drastically improve safety. A self-driving car could theoretically allow its owner to continue texting or uploading photos to Facebook.

“There is less error in systems than in humans,” said Mr. Ghosn of Renault-Nissan. “Computers do not drink or sleep.”

Carmakers also hope that self-driving technology could help arrest an alarming slide in auto sales among younger people. An increasing proportion of young people in developed countries are not bothering to get drivers’ licenses, preferring to spend their money on smartphones. The trend bodes ill for the car industry’s long-term health.

Mr. Ghosn speculated that governments could even lower the legal age for drivers. His reasoning seems to be that autonomous technology could help compensate for teenage immaturity.

Thomas Weber, head of research and development at Daimler, said he was not worried that young people would lose interest in cars. But he agreed that autonomous driving technology would be a crucial selling point in the future. Environmental concerns and changing tastes mean that V-12 engines and all-leather interiors are not as desirable as they used to be. The technology in the new S-Class, which Mercedes plans to offer in other models like the E-Class range and some sport utility vehicles, may already be helping the company regain ground it lost in recent years to BMW and Audi.

“To catch up and then to overtake, we need something where we are better than the others,” Mr. Weber said in an interview at the Mercedes stand in Frankfurt, which occupied an entire building. Mercedes designed the S-Class software in-house rather than buying it from a supplier, Mr. Weber said, and that will make the technology harder for competitors to match. “I am sure they cannot catch up fast,” he said.

When it came to the other big technological theme of the show, electric vehicles, the industry was polarized. Companies that are bullish on the prospects for electric cars, including BMW and Renault, have introduced vehicles designed from the beginning to run on battery power and look markedly different from conventional cars.