I just had a 2018 Optima rental car, more refinement than the Stinger? Are you nuts? Yes, it had a softer ride, that doesn't equal refinement. That is the ONLY thing the Optima had on my Stinger, oh yeah and that massive boot. If you want a soft ride, don't get a sports tuned car with low profile tires.
Let me explain in a bit more detail...
I found the Optima to be quite a bit more refined, in that while being feeling softer over bumps and imperfections, the body also bounced, pitched, and vibrated less over surface irregularities.
In addition, the Optima also smoothed out road grain and texture much more adeptly. This is evident in the steering, the seats, and the chassis as a whole.
A soft ride is not necessary, a composed ride is.
Roads that the Optima traversed quite serenely, would have the Stinger hopping/thumping/thudding/bouncing and sending jiggles through the chassis. The Optima actually has firmer body control than the Stinger. The Stinger suspension isn’t all that firm. The Stinger will fool the uninformed into thinking it is firm with its propensity to clearly communicate bumps and vibes into the cabin. That’s not a sports car. That’s lack of refinement. More accurately, it’s Kias tuning choices. Don’t mistake bumpy for sporty.
A sports tuned car, need not do any of these things...
Exhibit A. JAGUAR XE
Exhibit B. Cadillac CTS
Exhibit C. Plenty of other entries...
I do understand the effects of low profile tires and sports suspension.
Many cars pull it off more delicately.
And just FYI, don’t believe the marketing hype. The Stinger isn’t all that “Sport Tuned” in the suspension department. In fact, the springs are softish, the shocks too relaxed, and the roll bars diminutive.
The Stinger does benefit greatly from RWD and near 50/50 weight distribution.
Are you saying that you find the Stingers ride/handling mix to be without fault?