I was able to put an auto-dimming mirror on my 2018 Elantra SEL. Original one was fine, but definitely not better than the auto-dimming one.
It took me a couple of hours, but thats because this is my first major car project, other than changing interior/exterior bulbs to LED.
I fortunately did not have to remove the A-pillar (people are saying don't mess with airbags and the screw might break). That made it slightly easier. Final product looks awesome.
I researched the following two products before buying the one,
The reason was 1) price, 2) I never use compass, 3) don't need homelink, so a mirror with only the autodimming function was sufficient.
Hopefully this post would be useful to someone researching auto-dimming mirrors for their Elantra.