I have a 2013 santa fe with the 3.3L GDI. In Canada for our warranty to be valid we have to adhere to the 6000kms (3728mi) / 6 month interval. In the past 3 OCI's I've since switched to Motul xclean EFE 5W-30 which is an ACEA C2/C3 Dexose2 compliant 100% synthetic oil (I'm trying to find more information on this oil but it's proving difficult). It does seem to blacken the oil very quickly, but I wouldn't particularly say it smelled of gasoline, and the level never rises or drops indicating heavy fuel dilution or burn off.
My wife drives the car approx 6 miles twice a day to and from work and maybe a little bit of running around. We noticed when we'd go out on the weekend on the highway and I put my foot into it, it would PLUME smoke out the back and then clear up. Having said that I've also started to educate myself more with the GDI engines and we've decided with winter on its way, I would start commuting with the car approx 110kms (68mi) round trip because I feel it would be better for the car. It needs to have the C@&p beaten out of it quite frequently.
I am working currently on extending my OCI'S out to 10k kms (6200 MI) 6 months for ease of changing it at round numbers. I will be doing UOAs to monitor and see how it goes. I'll be sure to post up the results when I get them.
It appears to me that there is nowhere in the world where you would achieve the conditions to meet this "Normal" maintenance schedule. Seems like a money grab.
Aside from anecdotal "feely" evidence, Has anyone actually done UOAs on any of the kia/Hyundai GDI engines using a top tier synthetic oil to see how it's actually standing up past "Severe schedule" 3000 mile intervals?