Subscriptions are a popular business model of the early 21st century, and Tesla (TSLA -2.76%) is driving headlong into them. In a response to a tweet posted on Monday by a user named Whole Mars Catalog, reading "elon people are dying for [Full Self-Driving] when is it launching," the company's ever-colorful CEO Elon Musk tweeted "Q2 for sure."

The second quarter for calendar 2021 starts in four weeks. Musk had previously promised to deliver the subscription version early this year; at the time, he didn't get more specific.

A Tesla Model Y on the road.

Image source: Tesla Motors.

Full Self-Driving (FSD) is the carmaker's assisted driving system, which is currently available at $10,000 as an option with the purchase of a new vehicle. The FSD option originally had a price tag of $8,000; the $2,000 raise was enacted in October.

It is not yet clear how much such a subscription would cost, nor on what terms it would be offered. In a separate tweet, Musk only wrote that the outright purchase of FSD "will still be a better long-term deal than [a] subscription." 

FSD is rather a misnomer. It does not, in fact, offer "full" autonomous driving capability. Instead, it is a scattershot collection of features to help drivers with tasks like parking and lane-changing.

Tesla admits as much, writing on its website (with its usual dollop of hype): "While no Tesla cars are fully autonomous today and require active driver supervision, the FSD Computer is capable of delivering intelligent performance and control to enable a new level of safety and autonomy, without impacting cost or range."

Reviews of FSD, from both professional reviewers and Tesla owners, have been mixed.