Scoring a Taurus 80 for such a low price isn't something to take for granted and sell at a significant loss.
Between my family and I, I've had personal, first-hand experience with a total of 5 Taurus brand firearms, and so far they've all performed flawlessly. I actually currently use a Taurus Judge Magnum as my bedside Home Defense firearm.
Taurus gets a bad rep that I'm not convinced is completely deserved. They're good guns for the price, and in all honesty their rate of failure seems to be more or less equal to other major firearms manufacturers these days, but unlike others Taurus doesn't get the benefit of the doubt in the event that something goes wrong, and the hit or miss Customer Service certainly doesn't help either.
If it were me, I would keep it, take it out to the range to confirm function, then if all is well, put it to use as a vehicle defense firearm as you have been considering. Otherwise, take advantage of the lifetime warranty and send it in for service then wait until they get it back to you in proper working order.
At any rate, regardless of what opinions you may receive here, I would recommend at least giving it a chance before selling it off. It's not like firing a box of anmo through it is going to affect the resell value, especially not if you intend to sell it for a song.
Oh, and should you decide to sell it, consider listing it on the Taurus Forums, as I know a few guys there who are always looking to buy used Taurus' for cheap, functional or otherwise, so you could probably quicksell it there if you choose to go that route.