I have a manual shift 2016 Veloster Turbo. The engines are the same between the Turbo and the NA, just the Turbo and the tuning. The transmission also is different. The NA transmission shifts harder, I think it might be 5 speed. The Turbo shifter is more slick (thnk Golf R) and is 6 speed.
When I drive like an adult, I average 34 MPG on each tank. The NA does not move well at all, very underpowered. If you want better gas mileage, then you are better of looking at an Elantra, Civic, Corolla or even a Prius.
The DI injection turbo, does have some pinging when the weather is warm with regular gas, so I have to put mid-grade. Mine has 73K miles and just recently has started to use a bit of oil (0.25 qt/3K miles). I know that is not much, but we have a Sonata that was doing the same and now is going through 1 qt of oil every 500 miles. So, I am not very optimistic.
The Turbo kicks in at 1750 RPM’s, so it is pretty easy to drive it “without” the turbo for the majority of the time. You just end up using it when your life is being threatened!