If the scratch is visible to the eye from a very feet away, it's usually too deep to remove with a compound. For those I always wet sand. Compounds are great at removing swirl marks and very fine scratches. Deeper than that you will be removing too much clearcoat on too big an area and it's gonna take a long time to do. Also if you are too agressive with it you can burn the paint.
What I would suggest is to get fine sand paper (either 2500 or 3000 grit) and sand them out. If you are new to it, the trick is to sand very little at a time. I would start with 10 swipes, clean the area and evaluate. If it's still them, do 10 more swipes, clean, evaluate, and repeat until the scratch is gone. You will know from the first scratch how many swipes it took and you can do about the same for the other ones afterwards. Super fine sand paper with little pressure removes very little paint so it is safer to do than actually compounding like crazy. Just make sure to use a block and apply even pressure so you don't dig in the paint. I like to use the very small blocks that are sold by Geyon for applying coatings. They are like 1 inch diameter and 3 inch long. Wrap the paper around it and work it.
Once the scratch is gone, your compound will have not trouble getting the shine back.
The only thing I would not use this on at the present is Mazda paint. I have seen many of them have 50 to 60 microns total thickness. For Mazda, no paint correction or sanding is acceptable, there just isn't enough paint on the vehicle to do it. On a Hyundai like yours, paint thickness usually ranges from 100 to 130 microns, so you have some wiggle room to remove deep scratches.
Last thing, if after doing say 4 or 5 rounds of sanding, the scratch is still there, leave it be. It should be coming out in the first 2 or 3 tries. Going after scratches that are too deep will compromise your paint. You might not strike through it, but you will be leaving too little to give good protection. The exercise will still make the scratch much less noticable so you do get benefit from removing it partiallly.
Oh and very last point, stay away from edges and raised body lines. There is very little paint there so it's super easy to strike through, and removing sanding marks on those areas is also dangerous. So try to keep about an inch distance from either.
Ok, I think that's all
