Owners of certain vehicles equipped with its Super Cruise assisted driving system will now be able to use it on 400,000 miles (643,740 km) of North American roads according to General Motors Co, which doubles the current operating area as Tesla and other automakers race to deploy hands-free cruising technology.

Its Super Cruise system, like Tesla Inc.'s Autopilot system, is a driver assistance system and does not enable true autonomous driving. Spurred by Tesla's aggressive deployment of Autopilot and Tesla Chief Executive Elon Musk's promises of a more advanced "Full Self Driving" system, GM, Ford Motor Co, Volkswagen AG, and Mercedes-Benz AG are racing to deploy competing partial automation technology in major markets.

At the same time, safety regulators are showing concern that drivers do not understand that Autopilot and similar systems are not designed to take over driving in every circumstance.

The expansion, enabled by wider digital mapping, will allow owners of properly equipped GM vehicles to cruise hands-free on stretches of Route 66 in the U.S. West or the Trans-Canada highway in Western Canada, GM said.

Many of the new roads GM has mapped are in rural, heartland states where GM pickup trucks are popular. GM plans to offer Super Cruise as an option on its Chevrolet Silverado and GMC Sierra large pickups later this year. GM has said previously it intends to offer Super Cruise as an option on 22 models by the end of 2023. Depending on the model, Super Cruise costs $2,200 to $2,500 to add as an option.

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