It’s not a question of ‘if’: Sales will hit 11.8 million by 2035, IHS Automotive says.

Annual sales of self-driving cars worldwide — including those that require some driver input — will balloon from 230,000 in 2025 to 11.8 million by 2035, a new study predicts.

That would result in a cumulative total of 54 million self-driving cars in use around the world by that year, says consultants IHS Automotive.

It’s no longer a question whether such cars will be built, but how soon and how many. Already, virtually all major automakers are working on self-driving technologies. The experiments started with tech giant Google and have spread. The IHS report comes as the Consumer Electronics Show is about to begin in Las Vegas. Audi and Toyota unveiled self-driving technologies at the show last year, and more examples are expected.

By 2050, IHS predicts, nearly all vehicles — private and commercial — will be self-driving cars (SDCs). As more hit the road, the roads will be safer, it says.

“As the market share of SDCs on the highway grows, overall accident rates will decline steadily,” says Egil Juliussen, principal analyst for autonomous driver-assisted systems at IHS Automotive, who co-authored the study with IHS senior analyst Jeremy Carlson. “Traffic congestion and air pollution per car should also decline, because SDCs can be programmed to be more efficient in their driving patterns.”

About a third of all global SDC sales in 2035 will be in North America, IHS says.

Many cars already have precursor technologies needed for self-driving, such as lane-keeping assist and automated braking.

IHS says the first wave of self-driving cars will be limited to capabilities similar to autopilot systems on planes — the cars take over in relatively safe driving conditions, such as open highway.

Later in the 2020s, more sophisticated systems to handle more complex conditions will come to market.

But self-driving cars will come at a steep price, adding $7,000 to $10,000 to a car’s sticker in 2025, says the study. But then the price premium should steadily drop — to $5,000 in 2030 and about $3,000 in 2035.

There will be two big barriers to development: software reliability and cybersecurity. Also, the government will play a key role, setting the rules that will govern deployment.