Tesla customers are a passionate bunch.

Elon Musk's company has been promising for a while that, someday soon, its cars will be able to drive themselves. Currently, the (somewhat misleadingly named) Autopilot feature serves only to assist drivers during highway driving, and Tesla warns its customers to stay alert at the wheel when the feature is in use.

Last October, the company announced that all its new vehicles would be equipped with the hardware necessary for full self-driving capabilities. Before cars can actually zoom around without a driver at the wheel, though, Tesla needs to finish building out the complex, vision- and artificial intelligence-based software that will power it.

That day hasn't come yet, and Tesla has offered no timeline on when it will. Even so, according to a report from car blog Elektrek, about 35,000 customers have already paid for the Fully Self-Driving Capability package at $3,000 a pop. Elektrek did not name its sources in the report.

That would be about $100 million, if Elektrek's reporting is accurate, that Tesla would have collected for a feature that isn't out yet and that the company doesn't yet have government approval for. Tesla sells the self-driving packages with the caveat that the technology "is dependent upon extensive software validation and regulatory approval, which may vary widely by jurisdiction." A Tesla spokesperson did not offer Inc. an updated timeline on when it might be available, or confirmation on whether the figures cited by Elektrek were correct, saying, "Tesla's policy is to always decline to comment on speculation."

The 35,000 number represents about 40 percent of the 90,000 customers who have purchased Tesla vehicles since it began equipping them with Autopilot 2.0 hardware earlier this year. That hardware--which includes eight cameras, radar, ultrasonic sensors, and an Autopilot computer--will eventually allow Tesla cars to operate autonomously in conjunction with the software.

Tesla also offers the Enhanced Autopilot feature, which is the base Autopilot package for vehicles with the new hardware. That package runs $5,000, and it's required in order to buy the $3,000 Fully Self-Driving Capability package. About 77 percent of buyers of Autopilot 2.0-equipped cars have purchased the Enhanced Autopilot.

Tesla customers who don't buy the full self-driving package up front have the option of paying $4,000 later on, so it's likely that the $1,000 savings play a big role in their decision to buy it up front. Still, $3,000 is a lot to shell out for a product that doesn't exist yet. But Tesla customers evidently believe that Musk will deliver on his promises, as he tends to do--all together now--eventually.

It's worth nothing that the approximately $100 million Tesla has made off these purchases would not be counted toward the company's revenue numbers. Tesla posted a net loss of $336 million in this year's second quarter with a revenue of $2.79 billion.

Tesla has said that, before the end of 2017, it plans to send a driverless car cross-country to demonstrate its technology.