That’s a question some Tesla Model 3 owners are hearing a lot lately as they deal with a mysterious performance issue that’s keeping their cars parked where they sit.

The story begins with a post at the Tesla Motors Club forums, where a Model 3 owner in southern California complained that their car refused to be moved, saying it wouldn’t even shift into neutral so it could be rolled down the owner’s steep driveway.

Then, another owner’s car wouldn’t turn on at all, flashing warnings like “rear motor disabled” that a reboot of the car’s electronic systems didn’t fix.

A third poster replied to say their experience was a combination of the first two, but was able to get the car going and surmised the fault was caused by a bug in newly-installed firmware that had recently been introduced through Tesla’s over-the-air update system.

Staff at a Tesla service centre told the original poster the problem did indeed stem from the car’s firmware, which got confused when the driver began moving the car with the seatbelt unbuckled.

There’s an argument to be made that forums like the Tesla Motors Club are nothing but “gripe” sites where owners gather to discuss all the things that bother them with their cars.

But based on years of used car research we’ve done using discussion forums, we think that the four or five owners who have experienced this common flaw in the relatively small forum community means there are enough other Model 3 owners having similar issues that this could represent a major warranty problem for Tesla. All of the cars in question seem to have been built in the last couple of months, which coincides with when Tesla was finally able to start turning the Model 3 out in significant numbers.

And this isn’t the first time the Model 3’s build quality has been called into question; a Detroit consultancy recently did a tear-down of the car and proclaimed it was built like a Kia in the 1990s.

This is exactly what the electric car maker doesn’t need, given how much trouble Elon Musk and company have had in getting production of its most affordable car in gear, much less making the vehicles reliable.

(Hat tip to TTAC)