WILLOWS, Calif. — Faraz Khan’s all-electric Kia Soul is his workaday car, but on a drizzly weekend last month, he and his teammate, Jose Rojas, were hoping it would drive them to a racing milestone. So they squeezed on safety helmets, booted up their laptops and inched toward the west track of Thunderhill Raceway in rural Willows. Poised behind the wheel at the starting line, Mr. Khan stared into a laptop balanced on his partner’s knees. “In theory, this should work,” he said. “Although it might be an embarrassment.” The two men laughed off their nerves as Mr. Rojas initiated the car’s homegrown autonomous controls.