I've been comparing the maintenance requirements for the Elantra to my sister's 2018 VW Jetta. Big difference in favor of the Hyundai. But here's the trick, in my opinion. Hyundai-Kia has long maintenance intervals that my mechanic thinks are unrealistic. 10,000 miles between oil changes (for full synthetic) are stretching the oil and oil additive's ability to clean and lubricate. Whether it is dino oil, synthetic blend or full synthetic, the same amount of combustion byproducts are absorbed by the oil. Cleaning that grit out early is a good idea.
I follow Hyundai's severe service maintenance recommendations, which means I pay a little more over the life of the car, but my cars last a long time and are more valuable at trade-in time. I owned a 2011 Hyundai Sonata with the infamous Theta II engine that typically grenades due to rod bearing failure between 75,000-100,000 miles (Hyundai lost a very expensive class action lawsuit over these failures). My Sonata ran perfectly for 10 years, probably because I changed the oil every 3,000 miles. Still see that car tooling around town with its original engine.
I read in a technical magazine that the alloy used in Hyundai-Kia engines is a touch softer than that in Hondas and Toyotas. Best to keep things slippery down there, I think.
Since I have a good dealer all of maintenance is done there. First, the dealership is going to have the correct OEM parts, oil and filter which is most likely better than what you buy at the auto parts store. Having all my maintenance records at the same dealership will be helpful if I have a warranty claim. Their free multi-point inspection is one more set of eyes that can detect a problem in its early stages. Since I watch for online coupons from Hyundai or the dealership, I usually get my maintenance at the same cost of the discount guys.
Keep us informed on your purchase and how well you like the Elantra. Curious to see if you like it better than the HHR. Going from a conventional transmission to a CVT may be your biggest difference. For me, it brought back slip-sliding memories of the old two-speed Chevy Powerglide transmission. But I don't complain -- I get 33 mpg in the city and 44 on the highway.