That's between you and the dealer but ultimately the question boils down to "buy or don't buy"
You can ask them to fix it, either they'll say yes or no. Maybe they'll let you walk, fix it and sell it to someone else in a month. It might still be under the 5-year/60k mile factory powertrain warranty still - which they shouldn't have an issue with, but it's probably right up on the line if not over. (10 year/100k is for the original buyer only)
Purchasing a warranty may be sketchy if you discover a problem as it will be a preexisting condition and they probably have fine print banning that. and also one could say it's fraud. But any warranty may cost more than the price of just replacing it. (I wouldn't bother with this)
You could ask for a discount, you could ask for a $5 Chipotle gift card to be thrown in, whether they agree or not, you decide what you're willing to pay, they decide what they're willing to sell at.
Got a Subaru Outback inspected a couple years ago, drove nicely to the mechanic but it had a headgasket, cam carrier leak, stuck fuel gauge, etc. Dealer refused to discount it more than $1000 (roughly) so I walked, the sales guy said they'll send it to auction, but who knows what happened to it.
What I would not do is buy it first and ask them to fix it after if the promise was not already in writing.
I mean if you don't like it, you don't like the car. A lot easier to get rid of an imaginary car than an actual one. Compare with what the alternatives are. I didn't buy my Sorento because it was the best car out there, just that it fit my requirements (at the time) best. It's good your researching, but at the end of the day you only have so much information and while you can identify likely trouble spots, it doesn't mean any given car can't have a bizarre unheard-of problem.
