Hello there! Congratulations on your purchase! I'm also a recent owner..... and definitely not an expert, but I think I can answer most of your questions!
1. The petrol engine's recommended fuel is 91 Unleaded, but has the capability to run on E10 as far as I know. You can definitely stick with 91, but numerous mechanics that I've used have always recommended filling up with 98 Unleaded every once in a while just to give your engine a clean.
2. I just purchased the Active X as well, my car did not come with "dark" tinting, but it does come with a certain level of "clear" tinting, which blocks some undetermined amount of UV. I don't think the front windshield has any tint. I'd super recommend additional tinting, especially since you have those Leather [appointed] seats! (I'm also looking at tinted windows.. and am on the fence between 3M Colour Stable and Crystalline tint... but leaning slightly towards Crystalline due to its heat repelling properties... although it is more expensive than standard tints)
3. I'd have a mechanic take a look at the filters in your car, especially those that have to do with the air conditioning. They may be very dirty. I'd recommend changing it out, and see how that goes. If that doesn't help, there are professional air conditioning cleaning services that have antimicrobial treatments... But if it's not from the car and from the seats etc... then I'd have to recommend deodorising products and sprays.. or get it professionally cleaned.
4. I've been recommended Carbon Car Systems for tinting - they use a precise machine to cut the tint films instead of the more traditional way (using a knife to cut around the edges - which could lead to damage to your window, seals etc.). But I don't know if that technology is standard...(?). I've got quoted about $350 for full 3M Colour Stable and $799 for Crystalline for my i30.
5. If the car doesn't have mats - GET THEM! It'll be much easier to clean than the actual flooring of the vehicle... I'd also recommend updating the software of the audio unit so that its up to date (to include Android Auto) if it hasn't already been done - should be FREE to do at any Hyundai dealership (apparently doesn't take more than 15 minutes). I can't think of anything else... but if I do - I'll add them
Hope I've helped!
From one Active X owner to another - ENJOY YOUR CAR!
TREVOR!
