Google has built several prototypes of self-driving cars as the company moves away from modifying existing vehicles, the company announced on the Google blog.

The subcompact prototypes, which have no steering wheel, have been built with the primary focus on safety, according to Google. The cars have sensors to remove blind spots and can detect objects out to a distance of more than 200 yards in all directions. The speed of the cars has been capped at 25 mph.

The spartan interiors offer two seats with seat belts, a small cargo space, a button to stop and start the car, and a screen that shows the car's route.

Google plans to build about 100 prototype vehicles by the summer, when Google drivers will begin testing early versions of the cars with manual controls.

"If all goes well, we'd like to run a small pilot program here in California in the next couple of years," said Chris Urmson, director of the self-driving car project. "We're going to learn a lot from this experience, and if the technology develops as we hope, we'll work with partners to bring this technology into the world safely."