How close are self-driving cars from moving from the drawing board to a road near you? By 2025, the full universe of vehicles with some autonomous features, such as highway autopilot or autonomous valet parking, is expected to reach 12% to 13% of car sales globally, representing a market of about $42 billion for those features, excluding the base price of the cars, according to the Boston Consulting Group. By 2035 — about the time today’s toddlers will be out of college and in the car market — sales of fully autonomous vehicles will comprise 9.8% of the global market for new light vehicle sales, or about a $38 billion market for autonomous-vehicle features, according to BCG. That means a significant rollout of new-from-the-ground-up autonomous cars “may take decades,” as the 262 million registered passenger vehicles on U.S. roads now carry an average age 11.5 years, Glen DeVos, vice president of global engineering and services at car parts supplier Delphi Automotive ( DLPH ), told a Senate committee last month. The two-hour hearing before the Senate Committee on Commerce, Science, & Transportation featured testimony from top leaders of the self-driving car efforts at Alphabet ( GOOGL )-owned Google, automaker General Motors ( GM ), ride-hailing service Lyft and Delphi, all firms that are positioning themselves to profit from cutting-edge technology its proponents say could alleviate traffic jams, lead to a reduction in driver-caused car accidents and deaths, and even bring newfound travel freedom to people who are elderly or blind. Besides noting how far the technology has come, legislative experts at the Senate hearing also shed light on the numerous safety, regulatory, infrastructure and other concerns that the advanced technology must overcome if auto-drive vehicles are ever to become commonplace. Read on for a primer covering where self-driving cars now stand. Besides Google, what other companies are working on self-driving cars? Google, the public face of the self-driving car development effort, says its test fleet of autonomous cars and SUVs has driven 1.4 million miles since the effort started in earnest in 2009. That’s paltry compared with the 1.4 million miles that New York taxicabs collectively cover in just over a day, according to Senate hearing testimony from Mary Louise Cummings, director of the Humans and Autonomy Lab and Duke Robotics at Duke University. Before autonomous cars can be deemed as safe as human drivers, Cummings said, the Rand Corporation think tank believes the technology needs to have driven 275 million miles, fatality-free. So far, Google’s auto-drive fleet has been tested in California, Texas, Washington and Arizona. Apple ( AAPL ) is also reportedly working on a self-driving car, although the company has not commented on its plans. Other tech firms developing auto-drive vehicles include the “Google of China” — Baidu ( BIDU ), the country’s No. 1 Internet search provider. The company’s “deep learning” artificial intelligence research lab has been working on its project for three years. In December, Baidu announced that its modified BMW 3-Series had completed an 18.6-mile lap that included highways and side streets around capital city Beijing. The Chinese web giant was readying to test its self-driving cars on American roads. Baidu has been developing technology related to the car at a research center in California. Underpinning the self-driving car project is Baidu’s data-mapping service. Baidu is also pursuing the development of computer vision and other necessary technologies. In March, Detroit auto giant GM signaled its self-driving car intentions by announcing the acquisition of Cruise Automation, a San Francisco-based maker of driverless car technology. Cruise’s main product, the Cruise RP-1 autopilot system, can be installed in cars made by Volkswagen ( VLKAY )-owned Audi and those made by Nissan ( NSANY ), owned by Renault. GM, which says it has more Internet-connected cars than any other original equipment manufacturer, also said it has established a separate unit for autonomous vehicle development. That group will produce cars offering hands-free automated driving on freeways with proper lane markings by 2016. GM said, however, that drivers will have to be ready to take over control of the vehicle and cars will be fitted with a device designed to alert the driver to pay attention, even as the car self-navigates on the highway. Last fall, Tesla Motors ( TSLA ) began introducing advanced Autopilot software features, such as the ability to steer within a lane and change lanes on the highway, after outfitting its electric cars with the necessary hardware starting in 2014 — but it stressed that Autosteer is still in beta-testing stage , with drivers required to “remain engaged and aware” with hands on the steering wheel. This year, Tesla introduced the first version of Summon, in which drivers can use a smartphone to prompt their Model S or Model X cars to open a home garage door, drive in, park themselves and shut down. Once they’re ready to go again, drivers can use the technology to summon the car to leave the garage and come to them, which Tesla said could eventually eliminate “the burden of having to squeeze in and out of tight parking spots.” Ford ( F ) announced in 2013 that it’s working on a car that drives itself, while Renault and Nissan CEO Carlos Ghosn has said that his companies plan to offer 10 autonomous-drive models by 2020. Volvo, already testing auto drive cars in Sweden, said last week that it is expanding the testing to China. Volvo is wholly owned by China’s Zhejiang Geely Holding Group. Other carmakers are planning to release vehicles with various “advanced driver assistance systems” — including Toyota ‘s ( TM ) crash-avoidance technology for Toyota and Lexus models — by 2017. And some such technology is already on the road. For instance, Daimler ( DDAIF ) offers a system on certain models that allows a car to brake, accelerate and remain in its lane without human intervention at speeds of under 16 miles an hour, according to a February 2015 report from the Insurance Information Institute. Daimler, Volkswagen, Volvo, BMW, Tesla and several other automakers have complex self-driving car projects underway. U.S. auto safety regulators said this month that 20 automakers have agreed to make automatic emergency braking standard on nearly all U.S. vehicles by 2022, a move that could prevent thousands of rear-end crashes annually. How much will fully self-driving vehicles cost? The Boston Consulting Group estimates a sticker price of $10,000 above a regular car’s price for fully autonomous capability. Why so much? A wealth of technology is required to make the systems work, and many companies are involved in their development. Within the vehicle, those expected to cost the most include Global Positioning System, or GPS, units. There’s also LiDAR (Light Detection And Ranging), a laser beam technology used in police speed-detection guns. Using reflected light coming from everything around the car, the system creates a real-time 3D map that can be used as a guide to help keep the vehicle on the road and at a proper distance from other cars. Video cameras, sensors using radar and a central computer to analyze all the information coming in make self-driving systems work and are expected to drive up the vehicle’s price tag. “In an automated future, we need to be able to communicate not just with the driver or the owner, but also the surrounding environment. Knowing when traffic signals are going to change and where vehicle traffic is heaviest not only adds to the safety of the vehicle, but also allows the cars to be driven — or to drive themselves — more efficiently,” said Delphi Automotive’s DeVos. What other concerns did lawmakers discuss at the Senate hearing? Regulations governing the use of autonomous cars was a major issue. “Over the past two years, 23 states have introduced 53 pieces of legislation that affect autonomous vehicles, all of which include differ approaches and concepts,” said Chris Urmson, director of the self-driving car program at Google X. The laws could makes it more difficult to get self-driving cars on the road in some states or make it harder to take a self-driving car across state lines. To bring some regulatory certainty for the companies, the Department of Transportation is in the process of creating a model policy state regulators and lawmakers could use to craft their own self-driving car regulations. The federal government is aiming to define best practices for operating self-driving cars by the end of July. The National Highway Traffic Safety Administration (NHTSA) will work with states and the American Association of Motor Vehicle Administrators — a group representing state motor-vehicle agencies — to craft a path to consistent autonomous-car policies to avoid a patchwork of state regulations . The issue of retrofitting older vehicles with the new technology also arose. When asked which regulator would carry responsibility for overseeing quality standards if older cars were outfitted with auto-drive features, GM Vice President Michael Ableson said, “We don’t see this technology necessarily being applicable as far as retrofitting to vehicles. You need to touch a number of the fundamental systems in the car. You need to design in redundancy that’s not here today. The idea of trying to take that system and somehow retrofit it on an existing car? We don’t see a path to be able to do that.” Cyberhacking was a major issue raised, as was the need for driver privacy standards for self-driving and Internet-connected cars, which have been likened to “computers on wheels.” Last July, Sens. Edward Markey (D-Mass.) and Richard Blumenthal (D-Conn.) introduced legislation that would require automobile manufacturers to build IT security standards into connected cars. The so-called SPY Car Act (Security and Privacy in Your Car) would direct the NHTSA and the Federal Trade Commission to create IT security and privacy standards to secure high-tech cars and protect drivers’ privacy. The proposed legislation also establishes a rating system — or “cyber dashboard” — to tell consumers how well the vehicle protects drivers’ security and privacy beyond those minimum standards. Other concerns included safety and whether some technologies may not work in certain conditions, such as in cities with tall buildings could that block GPS signals or in extreme weather such as heavy rain or snows that could render LiDAR useless. What’s with ride-share company Lyft’s involvement? Getting people to try summoning a ride in a self-driving car could be a baby step toward widespread adoption, according to Lyft. That company is working with GM to bring self-driving cars into its program and let people warm to the experience of self-driving technology without having to buy it, Joseph Okpaku, vice president of government relations for Lyft, told the Senate committee. GM has also entered into a strategic alliance with Lyft and formed Maven, its brand for car-sharing fleets planned for launch in various U.S. cities. That might be a tall order. A survey released by AAA in March found that 75% of 1,800 drivers polled would not feel safe riding in an autonomous car, although 60% of them would be open to a self-driving car feature, such as automatic braking or self-parking, the next time they buy a new vehicle. Are any automakers shunning the industry’s self-driving car push? That would be high performance carmaker Porsche. “An iPhone belongs in your pocket, not on the road,” Porsche CEO Oliver Blume told a German newspaper earlier this year. At a public hearing on Friday held by the NHTSA, the Global Automakers industry group asked U.S. officials to slow down while creating regulations for autonomous driving technology. NHTSA said in January that it is working on new guidance on self-driving vehicles to states and automakers, aiming for a release by July. In the meantime, several speakers at last week’s hearing said self-driving vehicles are not ready for prime time, citing their inability to operate in snow or react quickly enough if others behave recklessly on the road. “Self-driving robot cars simply aren’t ready to safely manage too many routine traffic situations without human intervention,” Consumer Watchdog privacy project director John Simpson said at the hearing. “Deploying a vehicle today without a steering wheel, brake, accelerator and a human driver capable of intervening when something goes wrong is not merely foolhardy. It is dangerous,” Simpson testified. In December, California proposed state regulations that would require all autonomous cars to have a steering wheel, throttle and brake pedals when operating on state roads. A licensed driver would need to be in the driver’s seat ready to take over in the event something went wrong.