Steering was slightly clunkier, and not brain-controlled. They installed a windshield wiper motor fitted with a potentiometer on the steering wheel. A head-mounted gyro for the driver provided some steering so when the Spencer turned his head right or left, the steering wheel responded.
For safety, the code included an emergency brake in case of failure, the user had to hold a dead-man's switch in order to broadcast a signal, and a block wedged behind the accelerator prevented the Tesla from going too fast. And, at worst, the passenger could kick the actuators away from the pedals.
Granted, once it went, the Tesla wasn't quite between the lines and probably would have dinged the neighboring sedan if Spencer didn't think hard enough about stopping. But those few feet represent an incredible surge into the future.
A year ago, Spencer created a brain-controlled golf cart (video) dubbed the "Cranium Cart" for Cal Hacks. Potentially wrecking a golf cart isn't the same as risking a $85,000 Tesla, but Spencer clearly isn't afraid to put his car to the test. He is upfront about participating in Tesla's referral program, too, which probably helps.
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In September 2015, he became the first person to break the 500-mile limit by going 550.3 miles on a single charge (video) going about 21 mph across two states with no stops. Earlier this year he pitted the Tesla against a 2015 BMW M4 (video).
"I especially love going the extra mile," Spencer wrote on his YouTube channel. "Mostly because it doesn't cost anything."