Alphabet Inc.'s Waymo self-driving car division plans to roll out a driverless taxi service, an industry first, by year's end. Ahead of the launch, its early riders program is providing crucial feedback.

"The primary focus of our early rider program is really to have them give us feedback about what they want out of a service like Waymo,” Liz Markman, Waymo communications manager, told KTAR News in a report published Thursday.

Perhaps the 400 riders involved in the program will be part of history; they're the first people to regularly use a self-driving car. The early riders program began in April 2017 in Phoenix, and more than 20,000 people applied to be part of it. From that group, 400 individuals were chosen, and Waymo said it's gathered valuable feedback from them that will shape its future self-driving car services.

Insight includes a way for riders to communicate with a human being. Waymo found that riders often have many questions while the car shuttles them to their destination. So, the company is working on a communication system that opens up dialog via a button or smartphone app.

Another important bit of feedback is the need to develop a way to wake passengers who fall asleep during the ride once they reach their destinations.

The early rider participants are truly beta testing the future.

Those involved in the program are a diverse bunch. The riders range from ages 9 to 69 and come from various backgrounds. Passengers have used a Waymo self-driving car to get to work, go to school, go shopping, and run other daily errands.

Aside from the Phoenix-area self-driving cars, Waymo added that its national fleet of cars travels 24,000 miles daily. The figures don't include simulated driving where self-driving cars can "practice" tough scenarios that could be encountered in the real world.