Weight, track and how Genesis tuned it is all different. It's apparent that there is a similar platform and driveline bits but any review that has seen both points out the turn in speed and sharpness of the G70 over the
Stinger. Having driven both I can confirm. I didn't find any issue with
Stinger handling though, ive clearly gotten to that point where a grand touring tuned suspension is perfectly good either way for me
For the hatch space I'm dubious about the cargo space being that additive. It is cubically larger however I'd take a closer look at it from a usuable space point of view. I think one review, car and driver I believe, pointed out it didn't take that much more over a typical trunk in the class until you flattened out the rear seats. The extra rear legroom was the primary appeal for me there.
Both great rides, really should drive both and see which feel ends up feeling best. For us in the end we've decided G70 because of price/lease rate.
I got a call from the absentee Kia guy today and told him he had a $80 gap to make up and Genesis just dropped lease rates to 1.4 so not sure what he can do. He was going to look though. I've started the financing process with Genesis so the clock is running.