General Motors (NYSE:GM) is gearing up to expand its testing of self-driving cars in its home state. CEO Mary Barra said on Thursday that the General will "immediately" begin testing self-driving Chevrolet Bolt EVs on public roads in Michigan.

GM also announced that the next generation of self-driving Bolt test cars will be built on the Bolt's assembly line at GM's Orion Township assembly plant. 

A Chevrolet Bolt EV equipped with a prototype self-driving system drives by the GM Technical Center in Warren, Michigan. Image source: General Motors. 

GM is expanding its testing of self-driving systems on public roads

It will be the first testing of fully autonomous vehicles by a major automaker on public roads in Michigan following passage of a new law that expands what is allowed for self-driving vehicles on Michigan roads. The new law allows:

  • Testing of vehicles that lack steering wheels, pedals, or humans in the driver's seat.
  • Self-driving ride-hailing services.
  • The sale of self-driving vehicles, once the technology has been certified as safe.

The bill's supporters, which included GM, argued that the law would help put Michigan in the forefront of the development of self-driving technology, ahead of other states (including California) that have stricter limits.

GM's move to test in Michigan is an expansion of efforts that have been ongoing for several months. Self-driving Bolts have been spotted testing in San Francisco, California, and Scottsdale, Arizona. San Francisco is the home of Cruise Automation, a self-driving start-up purchased by GM earlier this year that has since become a key center of GM's self-driving research and development.

"Revolutionizing transportation for our customers while improving safety on roads is the goal of our autonomous vehicle technology, and today's announcement gets us one step closer to making this vision a reality," Barra said in a prepared statement. "Our autonomous technology will be reliable and safe, as customers have come to expect from any of our vehicles."

Where will these tests happen?

GM has already been testing on the campus of its huge technical center in Warren, Michigan. Initially, GM said, it's expanding the test drives to the roads around its Warren campus. The testing will expand further to roads in the metro Detroit area within a few months. 

Why does GM care about testing in Michigan if it's already testing elsewhere?

For starters, Michigan is GM's home state and the site of its huge technical center in Warren. And GM no doubt likes the flexibility available under Michigan's new law. 

But there's another important factor for testing self-driving vehicles: Unlike San Francisco and Scottsdale, Michigan gets plenty of winter weather. Snow and ice present special challenges to a self-driving vehicle's cameras and sensors. Early self-driving prototypes have struggled to stay in their lanes when lane markings in roads are obscured by snow, and have been confused by icy or snow-covered surfaces. 

Extensive testing will be required to master those challenges before the systems can be brought to market. A Michigan winter offers an excellent opportunity to do that testing. 

Is it a big deal that GM is building the next test cars in Michigan?

Yes. The current test cars were pre-production Bolts that were retrofitted with prototype self-driving systems. Building the next test cars on the Bolt's regular assembly line is a step closer to putting them into production. GM said the new test cars will have LIDAR, cameras, sensors and other hardware built and installed to GM's regular manufacturing quality standards. 

It's likely that the sensors on the new set of test cars will be more fully integrated into the Bolt's body structure rather than plopped on the roof as with the current test vehicles. 

What does this mean for GM shareholders?

GM is expanding its testing of self-driving electric cars and gearing up to produce a new generation of self-driving electric test cars on a regular assembly line. That suggests that GM is getting closer to putting these cars into production -- and it also suggests that GM's self-driving efforts are ahead of many rivals, both in and out of the traditional auto business. 

For GM shareholders betting that the General will be a winner in the coming technological transformation of the auto business, today's news is a good sign.