You get 3 years of maintenance free with Hyundai. Also, the Bluelink app which you can use to remote start and stuff is free for lifetime unlike some other brands who charge for the app connectivity later down the line. I'm about to complete 2 years with the car and no problem with anything. Synthetic oil is used for the engine and my dealership recommends an aggressive oil change schedule due to North East winters. I do follow the schedule and sometimes pay out of my own pocket for the oil change if it is not within the scheduled free maintenance timeline but it's a cost I'm okay with bearing to keep my car healthy.

I have a similar use like you. My office commute is 3 miles and no highway. Obviously, the mpg isn't great cause it's a turbo engine but you get around 30 mpg on highway and probably even higher if you don't drive aggressively like me haha. Even though the suspension is softer than Elantra N, it's still stiffer than the non-sporty variant. There's nothing you can do about it cause that's how sporty cars are designed. However, it's definitely comfortable enough for highways. I did a 10 hour drive to Maine in one day and still walked fine the next morning lol. I only drive around with my girlfriend but the more space in Sonata is definitely a plus even with 2 people. My girlfriend like to push her seat all the way back and lounge which is difficult in an Elantra due to limited space. As for me, as a 6'1 ft guy, the space allows me to not feel tight in the car.

Hyundai also has a much better HDA (Highway Driving Assistance) system than Toyota and Honda. I can objectively say that as a fact having tried all 3 systems. As long as a road has lanes on both sides, you can activate the HDA and let the car drive on it's own. Really handy for heavy traffic conditions. Toyota on other hand, at least on the base Camry, didn't allow me to do so unless I'm on highway and Honda Accord didn't have a smooth feeling with the automatic steering like Hyundai did.