Is the public transportation system good enough that you don't need a car?

So I lived in Dallas for about a year and a half, and to my recollection the DART system over there was good enough that I never needed to drive to get around to most places, since I didn't drive back then and I still don't, I remember thinking that going carless in Dallas is totally doable with some adjustments.

But what about Austin's public transportation? When I Googled it apparently Austin's public transportation is supposed to be pretty good, but when I go on Reddit I hear mixed things.

Is Austin's system good enough that going carless is doable for living there? Are the trains and buses reliable enough?

Because if it could be at all avoided, I'd prefer to use public transportation since driving is not part of my lifestyle.