Auto makers and Silicon Valley are locked in a fight to conquer the last bastion of screens, a frontier worth billions: car dashboards.

Dashboard display, and its revenue-generating ads and services, will compete for driver attention as much as phones do now. For instance, on future screens, local restaurants, doctors’ offices and other services could target ads based on typical driving routes.

‘We see this as the battle for the fourth screen’ after the television, computer and mobile phone. Ky Tang, an executive director at Telenav Inc Some car makers are turning over their dashboard operating systems to Alphabet’s Google GOOGL, -0.66% entirely, the Wall Street Journal reports . Not to be outdone, competitor Apple AAPL, +0.67% is pushing for its familiar screens and apps inside vehicles.

Certain carmakers themselves, including Ford Motor Co. F, +0.11% and Daimler AG DAI, -0.43% , want to compete in display with in-house technology; Ford, for instance, scooped up a bunch of BlackBerry engineers in 2017. Volkswagen AG VOW3, -0.80% already has turned up dashboard-technology growth. Toyota TM, +0.38% is using a customized version of an open-source operating system called Automotive Grade Linux to run its connected cars and infotainment systems. The system made its debut in the U.S. on the 2018 Toyota Camry.

But their challenge is clear: auto makers start with a natural disadvantage. New car models are designed and engineered several years out and customers tend to hold on to their cars more than they do phones. Car companies had been reluctant to spend money on expensive electronics, and older car displays weren’t designed to be updated, the Journal reported.

Still, the launch of self-driving vehicles in the coming years could bring even more screens into the car, on and off the dashboard, as passengers get more time to work, shop or watch movies on the road.