Some engines can be damaged by running an oil that is too thin for cold start and warm-up running, especially with cold piston to bore clearances. For example there will be excessive piston and bore wear in the engine in my wife's Opel if anything less than a 10W30 or 10W40 is run in that engine, and similarly with my Triumph motorcycle which must run 10W40. There may be a reason why Hyundai specified 5W40, and often the 5W is more important than the 40.
I don't know why so many want to ad-lib with their cars. Hyundai is a big company which has built millions of cars and they aren't stupid. If the VT will run 0w30 or 0w40 or 5w30 or 5w40; don't you think they would put that in the handbook?
But it's your engine and not mine. Go ahead and run what your heart's desire.