The relentlessly hyped arrival of autonomous vehicles looms as the greatest disruption in personal transportation since Henry Ford’s moving assembly line started producing Model T’s by the millions. One word in that statement — arrival — is, however, doing a disproportionate amount of work.

Self-driving vehicles, despite being the subject of breathless media reports and in automakers’ strategies, remain years from being available to private owners. Scores of companies hold permits to test autonomous cars in California, yet even leaders like Waymo, once Google’s self-driving project, are unwilling to commit to when such vehicles might be appearing in showrooms.

Even with so many companies testing self-driving cars — 10 million miles since 2009 by Waymo alone — the definition of autonomous continues to be murky, at least to the public. What is available today in driver-assistance systems like Cadillac’s Super Cruise or Tesla’s Enhanced Autopilot may offer hands-free motoring in some situations, but they are far short of what is known as Level 5 full automation under the standards of SAE International, a standards-setting organization. That capability entails operation on any road in any conditions that a human driver could handle; logically, cars built to this standard would have no need for a steering wheel or foot pedals.

With this radical shift in driving comes questions about the viability of traditional business models based on the private ownership of cars and the dominance of the large carmakers.